Have a car with short ram intake (much less restriction than stock), and hedman headers/y-pipe and a catless cat-back exhaust. Don't have the money to go crazy right now because I'm a broke college student, but I've heard that with just exhaust and like the zz4 cam that you can achieve upwards of 275 RWHP. The intended use for this car is something that I drive for fun on nice days that will only see a track 1-2 times a year.
So my questions are,
1) With just intake and exhaust, will I have a noticeably higher power/torque output with a new cam?
2) If so, what are good BUDGET cams (seen the zz4 and lt4 hotcam posted a bit), and what results could I expect?
3) How much do these usually cost and where is the best place to get them?

Not black and white scientific facts per se, but.......

What was the zz4 rated at? 330 if I remember correctly? ...and that was using stock aluminum L98 heads, so minus the compression difference that we have with our iron L98 heads, it's more less the same head. (more or less). ...and if you're using a high flowing/upper RPM intake that would be closer to the carb GM uses on the zz4....well that should give you a pretty good "unscientific" ballpark. FWIW, I had a stock TPI intake on a zz4 cammed L98 with full exhaust and it was a night and day difference over stock. No numbers though. Still, not sure you'll get 275 RWHP.

I bought my zz4 cam as a 0 mile take out for $100 over 10 years ago, but they're gettin' a lot harder to find obviously. LOTS of similar cams, but not necessarily for a budget. Cam swap and "budget" don't often go together. ...plus, you'll need tuning, gaskets, tuning, sealants, nuts, bolts, zipties, etc. etc. ...and probably some tuning. Nothing is ever "budget" in my experience.

Is there such a thing as budget third gens?

Only if the word "budget" is preceded by the word "large".