You're starting out with a car that's already 22 years old. They were pretty good back in the day but how much longer do you realistically expect to get out of it? You can expect the usual kinds of problems that old cars experience as their parts wear out and deteriorate, particularly rubber parts such as seals and bushings.

If you can do your own repairs as needed it may work out OK. If you have to go to a mechanic every time something goes wrong it could turn into a money pit.

The GM 3800 engine was one of the best they ever made. The transmissions they were paired with however were often somewhat weak so somewhere down the line you may need a new one but given how long the engine will last it’s often worth it to put one in. That said you only paid $2500 so even if you choose not to put a new transmission in, if it lasts you a few years you’re still getting a good deal. Old Buicks are some of the most overlooked old school American land yachts so you can get luxury for cheap. You can often find much lower mileage ones for the same price you paid because a lot of older people buy them. Regardless, the mileage you have is high but not too high yet imo. Lastly, as Chuck stated, being that old expect the rubber parts to go out.