If memory serves, the B&D 8" saw has a stamped metal table and a direct drive motor (no belt). The most important consideration here is the blade bearing's play-out....i.e., how much play or wiggle is in the bearing. You can test his by putting in a blade, tightening up the holding nut and then (with the saw unplugged) run the blade up as high as it can go and carefully grab the top of the blade and move it from side to side. If you feel it clunk back and forth...even a tiny bit, this means your cuts may 'wander' a bit. If the blade moves more than just a tiny bit I wouldn't take it, even at $30.
Yes, there are lots of 8" blades out there, and in a pinch you can put in 7 1/4" blades. But this little saw really doesn't have enough umph to do even medium cutting, like rip a 2X., without overheating and stalling.
Check the worm-drive bearing play out the same way. The bearings on these kinds of saws rarely, in my experience, give out...usually, its the motor that goes first. At approx $130 new, if this saw works and has good bearings, its a steal at $30.
Best wishes, and get started on those projects! (smile)