I'm thinking of installing a spa at my house but the additional wiring for 220v is going to cost around $1k and I was wondering whether it's something I could attempt to do myself?
A 220/240 GFCI supply for a spa is not difficult. There are several ways to accomplish this. One of the more common is to get a "spa panel" that can be located close to the spa and serve as the disconnect and GFCI. These usually cost under $120, plus the feeder wiring. Many home DIY books cover the requirements, but it is a good idea to read up and ask questions first. Many states allow a homeowner to pull permits and do the work themselves. A few states require licensed electricians. So it is best to read up and find out what your local rules are. Call your local permitting office and ask what they require. Asking additional questions here can also help you out.
Yes this is something that is good to know, and it can save you hundreds in most cases and over a lifetime possibly many thousands.
Before getting started, do you know what the safety procedures are?
You need to know how to not get killed. Working on AC can very much make you dead.
This is the basic starting point: what can kill me at this phase of the DIY?
Once you are knowledgeable about the safety, do it at a pace that you're comfortable with, and without skipping any steps. Double and triple check everything, and don't skip any safety equipment.
If you are familiar with DIY projects, then this should be pretty standard, but the motivating factor should not be money. It should be your own satisfaction and comfort in doing this. $1,000 is not worth killing yourself over.