New garage speaker placement?

If this a system to listen to while you work, maybe some powered monitors would be the best way to go. They can be placed on a shelf or mounted to a wall. No need to fool around with an external amp. You would just need a source with a volume control. (ipod, tablet, notebook, etc...)

Yeah, never thought about those. What brands should i look at?

Your best bet is to go to a music store, like Guitar Center. They have brands like KRK, JBL, Tannoy, Adam, Mackie, M Audio, and probably some others I'm forgetting. To be clear, I'm not saying these type of speakers will be as good, or better than traditional audiophile gear, but for a garage where you won't be doing any critical listening, they should work nicely. I have a pair of Tannoy 502's I use on a computer. I know they make a larger one with an 8" woofer. For your garage, those would probably be best.

If you are willing to hang speakers on a wall instead of using within wall types, and for $500 and something that will sound nice:

Pioneer SP-22lr speakers ($129),
Pioneer A-20 amplifier ($270),
Pioneer makes a subwoofer that mates with the SP22s (i believe ~$130).

All values retail.

For this system you need 7.2 surround; nothing else will suffice! ;)

You may want to reconsider in-wall placement of speakers in the event that you will reconfigure the shop/work area. If you ever move things around within the space, you may want to change the location of the speakers.

Zd542 gives good idea on powered speakers. Another alternative is vintage gear. I have a lovely vintage Nikko stack with some monitors that resides on my oversized workbench.