Here's a link on the DVC boards about
people who have downsized their DVC ownerships for various reasons. It helps you think of what your needs might be in the future, some have added at other resorts as they plan on spending more time in retirement, some have let go of points because they burned out on Disney or are not needing as large of units as they used to when the kids got older, etc.
We own a combination of points both direct and resale. If you do decide to purchase, I would unequivocally recommend resale, unless in a few very rare cases one is trying to "add on" a smaller contract with a difficult use year at a small resort. You will save a ridiculous amount of money, and with the loss of some perks that are a terrible value, such as exchanging points for cruises which is usually much more cost effective to rent your points and pay cash for.
One of the main expenses is that you are committing to a Disney vacation every year, so you'll be buying tickets and airfare ... if you aren't going to be going anyways (at least every other year), don't buy. We were committed to going annually anyways. The other main budget consideration is that maintenance fees will far surpass the amount that you will spend on the purchase price over the life of the contract, so pick your resort and corresponding maintenance fees widely (most recommend SSR and OKW if you're planning on Florida every year).
All that being said, if you can plan in advance, are going to Disney anyways, and want to stay in a villa, it can be a good value for some. For us, we'd never stayed on-site before, but now we have a gorgeous villa on-property with 3x the space for the same price as we'd been paying to stay off-property in a small hotel room in Anaheim every year, so it was worth it to make the commitment to trade up. But the math will be different for everybody, so run some spreadsheets on what you anticipate spending on your hotel costs, and compare.
Another hint a lot of people say, is to buy half as much as you think you'll need to start, you can always add on later if you want to.