Sorry but my own opinion is that some of these answers go too far - though I fully understand why people express such caution. Take care!!!
Yes, buying land anywhere without a title may be a risk. However, land can be investigated and if a title is NOT owned by someone else and if other easily discovered factors are NOT true, then the and can be bought and a title applied for and obtained. I have bought 10 pieces of land, most without titles, since I first bought the two plots on which my own house stands so I'm fairly confident about this. Some now have titles and others will have soon.
A good lawyer (never one that's lazy or a cheat) must check if the papers that represent ownership of the land are legal. So, first, are the papers legitimate or fakes (such as photocopies - yes, people do try this!). Next, is their a bill of sale to show when your seller bought his/her land from his/her seller (land may not have a title but it always has a bill of sale unless the owner is the first to ever own it, rare now except for elderly owners of land in the countryside. If yes, check (your lawyer should know how) that it meets all the rules. It must be signed by all those with rights, at least the owner and always any spouse. An X for a signature is illegal, fingerprints are needed for illiterate sellers or buyers. Cedula or passport numbers and full names must be included and it's normal that a photocopy exists of these documents for all recent purchases or sales. Next, any documents must be checked in the Registration office. This will show who the current owner is - it may not be the person shown on the bill of sale or title you are shown. If names do not match, walk away. If a title exists and the Registration office shows the current owner is the same as the seller, you can probably buy (see below). If the land has no title or listed owner in the Registration office but an owner has a bill of sale to show he legally bought it, you can buy it and then seek a title. However, the previous owners should have owned it for quite a few years and have made use of it (ask a lawyer how many). Never buy land inside a National Park before checking what you can use it for (it's usually illegal to sell such land but that doesn't mean it cannot be bought!).
As usual, al things legal are complicated - get a GOOD lawyer. Fees should be fixed and known up front, not a % of the purchase price. RD$800 is a good fee for creating a new bill of sale for you. With a title, not much more, RD$3000 is tops (and too much!). Expect to pay extra as legitimate taxes (these can be large for large amounts of land - usually they're small) for which you should see proof of payment.
There's more to know!
Good luck.