For an inexpensive version, here is one I was eyeing for a build I am planning.. This is a JG and recently JG has stepped their game up... This one is said to be "Lipo Ready", but I dont believe that.. All AEG's req a little once over before really being Lipo ready IMHO...
http://www.airsoftpost.com/product_info.php?products_id=28591The above link is the cheapest Clone i could find that I would actually buy. $150 and free shipping... JG, and AGM are the same guns, so if you shop around you can find a lot of them avail at the many retailers out there... I also recommend to contact "Autogxt" on this site to see if he can get you one as well. He is our local retailer.
I have an Echo one 614 (416) and it is a great gun as well, but is at a higher price range than most clones (They offer 30 warranty). So far it gets the job done, but it has not been very impressive (Did not expect it to be)..
As will all AEG's, you can buy an inexpensive one, and build the perfect gun with upgrades.. And these days, upgrading is not too expensive if done correctly.. The hardest thing to do is the actual work installing, and also doing the necessary research to find out what items need to be replaced in order for you to have the gun you want performance wise.
Fit and Finish... A lot of the Clone 614/416's are plastic bodied guns. And this so far has not been a issue for me.. Upper and lower Receivers are plastic, and the front end is metal. This makes for an extremely light gun. I have thought of adding a metal body to mine, but I am enjoying its lightweight too much to change it.
On a tech standpoint, the 416 is no different than a M4/M16.. It is a Version 2 Gearbox, and everything else is exactly the same.. So working on it is no different than a M4/16.. Finding info on working on them is easy, and once you get the hang of it, you'll find it childsplay as well.
Parts galore internally... Being a version 2 gearbox, replacement and upgrade parts are avail in an abundance.
Good luck in your search...
Oh yeah, JG and AGM offer a Metal Version for $180, but noone has them in stock right now...