I'm getting ready to do my fist two builds, Yugo M70 underfolder and Hungarian AK63 based Kyber side folder. I am looking for a tool that is affordable for squeezing the long rivets.

A 12 ton press.   How affordable it is, I can't say.  But there is no way that I know of to get good results without one.  Those I've seen try to just hammer them, have the results one might expect.  Perhaps you have an acquaintance with an auto repair shop? They use presses all the time for suspension bushings.  Then you'll need a way to hold the receiver square and retain the rivet head  while using a ram to make the other side head.  I've come up with several different fixtures, but they are all variations of the AK Builder concept.

IIRC the 12-ton is going for $100 right now with the coupon. The rivet jigs are the way to go, just finished up a Romy build using the HF press and rivet jigs..

My first build I just used a ball peen hammer

Press is much easier

Tooth Tool all the way. Buy once and be done with it: http://tothtool.3dcartstores.com/AK-Long-Rivet-Tool_p_12.html

there are a few people out there who just do them in a bench vise.

I ended up buying a "Plinker" style riveting jig made by a machinist on another forum. Works sweet.