This will depend a lot on area, and need.
First, lets cover the builder's options to you. They both suck. You can have them do the work of running wires for way to much money, or you can get some unknown wireless router, for again, way too much. On this front your builder is just straight up ripping you off. On an existing, "normal" sized house (which is much harder to do), you could get a wire to every room, installed by your internet company (which overcharges as well) for around $200. If you hire a professional, it might cost you $100. Wire is dead cheap. You can get 1,000 feet of cable for around $150. You wouldn't use anywhere near that much for a normal house. With a central point (say your office) You might use 50 feet, maybe 100. If your trying to install from an outside room (the central point is in a room that is in one end of the house or the other) then you might use a bit more wire and end up using 200 feet, maybe. Remember, specially if you have an attic or crawl space, the wire doesn't have to follow any special path. You would normally just place it along side a beam or support to make it easy to find. In a crawl space you may nail it to the beam to discourage critters from chewing it, but in the attic you usually just lay it there.
In the wireless side of things. An AMAZING consumer grade wireless router would cost about $100. And even that's a bit on the high side. Shop around and I bet you can find a great one around the $50 mark. As for install, you take it out of the box and plug it in. It's honestly harder to install a toaster oven then it is a modern wireless router. In fact your ISP of choice will probably give you one, "free". Rather you should use theirs or not is not a topic for this site, but the fact is, if they give you one, why should you buy an overpriced one?
I am not a fan of most builders. Some are good, but most are not, in my experience, take that into consideration when reading this next part.
In my experience, if you get an option for a normal builder (building in a gated community/sub division) they like to sell you high priced options and then totally flake out on the install. Networking is a complex and nuanced field, even more so when your trying to "future proof" something like an install. There are people that make networking, and even cabling, their life's work. Your builder on the other hand is likely to assign this cable running task to the low man on the totem pole. The new guy, or the guy that no one likes. Or worse yet, to one in particular, and have it be just some odd task that needs to be done. They almost certainly do not contract out, or keep on staff a networking professional. So what your really getting for your $800 is a crappy networking install that could take you years to figure out is the source of all your woes.
For example, every nail, metal brace, and especially "normal" electrical cable, could adversely effect your wired install. Is that accounted for? Did you know there is a minimum turning radius for the cables used, and if exceeded could totally ruin the cable? What about "plenum grade" wires, did they use them in the right spots? Did they use a tool like a Fluke Tester (it's a brand but there are other brands) to test the cables and make sure that they are wired correctly? In a good install every "jack" gets two cable runs to help avoid failures and allow for future expansion, did they bother with that? For $800 those are the kinds of things I would expect. What your liable to get is an install that is a lower quality then if you were to do it your self.
Do you need wired Ethernet?
These days it's really hard to say that a home "needs" wired Ethernet. A good wireless setup (it's a bit more complicated then just plugging in a Netgear though) it usually more bandwidth then a person could use. The only real exception is in-house transfers. Even there, though, one needs to be realistic about their goals.
If you live in the US and your lucky, you have have a 1,000 mbps up 1,000 mbps down internet plan. However it's important to note that your only one side of a data transfer on the internet, and most (if not all) business sites including large ones like Amazon, Google, Youtube etc. will set a "speed limit" on a single connection so that you never get that much speed from them. Almost any internet related speeds are going to be lower then a good 802.11n setup. Transferring large files in house, or having many concurrent connections (every kid and adult watching a different Netflix show) will strain a wireless network more then a wired network, but you have to look at devices too. If everyone is watch on their tablets, a wired network isn't going to do you any good. Laptops these days are more mobile as well, so again, will a wired network even be used by most of your family?
So your best solution, to get good speeds, and a good network, is to do it your self or hire someone after the fact to do it for you. Your ISP should install their equipment into your "office" or wherever your primary usage is going to be. If you have a family server (We use one to do backups or store photos and such) then you can arrange to have the ISP place their "modem" right next to it, and use a wired connection for that box. Use a well installed wireless network for everything else.
Remember, that the wireless network they will install for you is almost certainly going to suck. A good network takes into account placement of walls, furniture (sometimes), appliances, and other noise sources. They can't do that till after you move in, and I highly doubt that's what they are offering.