New at this, starting my first floor in a couple of weeks. 650 s.f. of 3 1/4" - 3/4" oak

First question, when putting down the underlayment, how do I secure it? Staple gun?

Also, been seeing some nailers on ebay made by RAMSOND and another by Akio that look identical to the Bostich that this site recommends. I assume that these are Chinese knock offs, but I don't plan on doing much with it after I'm done with my floor. Is it worth buying for $150??

Thanks.

What type of underlayment are you putting down and what is it going over?
If I am installing 3/8" or 1/2" CDX plywood underlayment over wood subfloors, my system is to use my Senco general construction stapler. I staple the snot out of the plywood. It is fast, inexpensive and does a fantastic job. I do not recommended gluing underlayment unless you have to because if you need to remove it due to water damage or something of that nature, you will tear the hell out of the subfloor. Others use screws but I find that too slow and expensive. Staples for underlayment have been the industry standard for over thirty years.