if you are already a
DVC member, you can add-on at any resort, depending on availability...for a minimum of 25 pts if you pay cash or 50 pts if you finance. there are no closing costs for add-ons.
assuming you're not already a member, you can buy in at any resort, but have to buy a minimum of 160 pts. most guides are geared toward selling SSR and AKV, and may require extra effort to convince them that you're only interested in BWV or BCV, so you need to make this clear. there are closing costs involved buying direct, but they are generally smaller than buying resale.
i bought a small contract resale through TTS (this site's sponsor) to start my DVC ownership and had a great experience. you do need to watch out for resale contracts that have been stripped of current points, but most likely, you will save a little money by buying resale...if you can find a contract that you like.
(BTW, if you don't need 160 pts and are looking for a smaller contract, resale is your only option and your best bet is to call TTS and get on the email list for contracts that have yet to be posted to the website...small contracts can go quickly!)