Yeah, what do you play? CQB? Forest? Field?
If you're just messing around in a neighborehood or whatnot then I can help you the best since that's what I do and I was in the same position, exept I used a spring pistol against like Echos, GBB's, and whatnot. I'll try my best to get the best, but closest to 150.
Okay to start off with, the brands I would reccomend would be Echo1, G&G sportlines(may be 170 dollars), Cyma(newer models only, the rest are pure lpeg trash), and CA sportlines.
Okay, in my opion m4's are the best all around guns, so I would go for a Echo1 stag arms m4(Jg m4 with trademarks and slightly bettered internals), but it does come with a crappy battery, so I would reccomend getting a better battery. An Elite, Intelect, or PHX will do.
http://www.airsoftgi.com/product_info.php?cPath=280_281&products_id=1975
Like the m4, the g36 is another popular gun, and it's considered the best Echo out there. The rof isn't that great, it's about average, and the fps is typical, around 360fps. A big plus for this is that it has now metal ball bearings, witch is a plus.
http://www.airsoftgi.com/product_info.php?cPath=139_24_163&products_id=1974
For an AK model, I would go for the Echo/Jg one, or one of the Cyma ak's.
http://www.airsoftgi.com/product_info.php?cPath=139_24_150&products_id=2167
http://www.airsoftgi.com/product_info.php?cPath=139_24_206&products_id=3309
If you want a more compact type gun, the get a E1 Mp5, rof average, shoots at about 330fps, It will probably have a safety issue where the safety doesn't work and just switches to semi whenever shot.(common problem with this gun;I owned one. The Accuracy however, is the best amongst the echo1 g36 and m4.
http://www.airsoftgi.com/product_info.php?cPath=139_24_150&products_id=1976
http://www.airsoftgi.com/product_info.php?cPath=139_24_150&products_id=1972
If you want a higher quality mp5 with stock 370-420fps, then get the Echo1 Vector arms, though its about 175 dollars, and the Taskforce and Master series(MS not worth it) then you'd probably have to spend 180+. For the TF, get the new mp5 from Cyma. it's around 180dollars(make sure its not the crappy 80 dollar one).
look at the sources for the other half of the answer. Yahoo answers doesn't allow me to have over 10 links in answer box.