Recomendations?

Where should I buy them?

What tools are better than others?

Thanks for the help.

The only specialized tool needed would be a castle nut wrench if you are using a stock that needs it.

I'd also suggest a lower receiver vice block.  Midway sells one in a kit with the upper  receiver vice block. That and punches and you are good to go.

Castle nut tool or strap wrench. Then follow the tutorial on this site. That tutorial is one reason I re-up my membership every year, very useful.

A vise and a good torque wrench, plus the appropriate receiver extension wrench are what you need.  You can put the lower in the vise with wooden blocks to protect it (I put it in at the rear of the lower) for installing the receiver extension.  I've assembled the rest of the guts on a kitchen table and my lap using basic tools.  It is really straightforward, but someone without experience should follow the instructions TO THE LETTER until he gets a few guns under his belt.

You only need basic tools to assemble a lower.   A set of roll-pin punches is helpful and the csatle-nut wrench if you decide to go with a collapsible stock.

Building an upper requires additional tools.

Electrical tape to mask off all the areas near roll pin holes so you don't inadvertently ding or scratch your lower.

A gallon sized zip-lock bag is handy when installing the front takedown pin, detent & spring.  If you're not careful you can easily launch one across the room (thus the zip lock).

Although some say not to, I use a pair of Channel Lock pliers to press the roll pin into place.  Just make sure to cover the plier tips with electrical tape. I found it's easier than beating it in with a hammer. Seen a lot of broken ears on the trigger guard caused by a heavy handed hammer.

Best tips I can offer, are:  1.  Read the tutorial on this site. Best info around!!  2.  Take your time and work slowly!! No need to rush it and potentially damage your lower...

If using a hammer/punch to drive the trigger guard roll pin, must support the lower "ear" with a block of wood. For assembling lowers, roll pin punches, with the little nipples on the end, to center the punch on the end of the pin are handy, but many of us use the Vise-Grip method shown in the tutorial. I have Mayhew roll punches- from local tool shop- a 5/64-inch and a 1/8-inch are all I need/use for lowers.

There is also a video on how to do it- but if using a hammer/punches, go slower than the guy in the video does. I think the video is linked in the tacked thread on how to build a lower. For either the Vise-Grip method or with punches, when putting in a roll pin, cover the adjoining and surrounding surfaces of the lower receiver with electrical tape to avoid marring the anodized surface. Go slowly, at least for the first one. Happy building- you'll learn a lot.  

For me, I use vice grip pliers, scotch and electrical tape, a hammer, a cheapo set of punches I got from harbor freight (not needed but makes it easier), a screw driver (or whatever bit you need for the grip screw), a castle nut wrench (I use the DPMS milti tool as it has everything I need on it), and a box cutter.  In the future I plan to order the special tool from Bravo Company designed to put the detent in the front take down pin.  Its $5 and seems to be well worth it to avoid losing that detent.

I have done 2 and helped on a couple more and still like to follow the video on youtube.  It makes sure I don't do stupid things.  I found it more helpful than the write up on here honestly.

I just built my first lower last week. Only tool I needed to buy was a castle not wrench. Used taped channel locks for the roll pins. Not that I don't have punches, but channel locks were way easier. + you don't need a vise or a vise block when using channel locks.

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs121.snc4/36399_567301361427_6600408_32917557_8074658_n.jpg

I made my own vice-block from a piece of 2x4 using the magwell dimensions. I started the pins using a nail slid inside of the roll-pins, and finished them off with a normal punch-set from harbor freight once they were partly in. I used a taped-up razor-blade to depress the take-down detent pins. And then a whole bunch of painter's tape to protect the finish, expecially when driving in the bolt-catch.