Check the keel. Make sure it raises and lowers and is not too rusty to restore. Check out the keel winch and cable to make sure they are servicable. Get a rubber mallet and bang on the deck, especially around fittings, to make sure it isn't delaminated. Check the horizontal fiberglass stringers inside the hull to make sure they aren't cracked or deformed. Check the outside of the hull for deformation. If the boat has been on the trailer a long time with the keel raised instead of resting on the trailer, it can cause deformation. The deformation may or may not go away when the hull is in the water. Check the bottom of the hull for osmotic blisters. A few small hard pimples aren't a problem, but extensive blistering might be. Check the standing rigging for broken cable strands, cracks in fittings, etc. Also check out the running rigging and blocks to see what needs to be replaced. Check out the sails. A complete set of new sails can be had for around $1500 for OEM quality. Used sails in good condition will probably be half as much. Check out the mast and boom in raised position to make sure they are not bent. Chances are the nav lights will need to be rewired, unless the previous owner has already done that.
Make a list of everything that needs to be repaired or replaced, and estimate the cost and effort. Blue Water Yachts web site sells replacement parts for MacGregor boats, while Sailnet can quote you sails and rigging. If it still looks like a good deal, go for it. The V25 and M25 are fun boats and easy to sail.
Except for a delaminated deck or hull damage (broken stringers, extensive blistering, warped or severly dimpled) you can probably handle any needed repairs your self.
A couple more:
Sometimes the bow loop (for the trailer winch) is loose. Make sure it is tight. To fix it you have to cut an access hole to get tools between the interior liner and the hull.
The plate on the deck that the mast attaches to takes a lot of strain. Make sure the area around that plate is tight, and that the screws and deck are solid above and below deck.
The ceiling paint likely will be peeling, unless the owner has repainted the interior.
I bought a ven 25 last year and found that it is a good boat even for its age.
The boat had a few minor problems but these were soon remedied, with little cash, more time.
My windows leaked but theywere easy to fix,and the keel bolt needed to be tightened, lots of water coming in.The wiring was a rats nest but that is on my list of things to replace next year.
All in all I'm happy with the purchase. I think you will be also.