nostatic recommended some QSC speakers when I was looking for PA type stuff. I found a pair of K10's used and picked them up. They can take an output directly from an iPod or other MP3 player and have a built-in 1000W amp each. They sound pretty good for music but are not especially cheap if you have to buy them new. Figure $700 each new or maybe $500-550 each used if you can find them. I prefer to wait until I can find a used set of any of these suggestions. I bought mine from a wedding videographer that also did karaoke. He had used the system only a couple of times over the last year and figured he could use the money for some new equipment.
QSC K10
QSC K10 (10" 2-Way) | Sweetwater.com
Not as nice but some people like these also. Probably plenty loud in a garage. yCapable of 118dB at 1 meter. $350 each.
Mackie Thump TH-15A | Sweetwater.com
The other route is to get a good set of efficient speakers and as much amplifier power as you can get. Buy old stuff that does not do surround sound for the best bang for the buck. Klipsch is my choice for the money. Cerwin Vegas (get a set with 12 inch or 15 inch woofers) are cheaper but sound rather harsh to me. I only have a cheap older Yamaha Receiver right now but am considering trying a used Crown PA type amp for a few hundred. I think it would really make the old Klipsch speakers kick.
Klipsch
Klipsch F3 Tower Speakers
or these
Klipsch RF3 pair of tower speakers
Speakers may be too large but here's an amp for you.
Starter PA w/ Amps
Be patient as there is always a good deal on a nice piece that will come up sometime. Just save the money so you have cash on hand ready to snap up a good deal when it comes along. A daily 5 minute search of searchtempest.com will eventually yield what you would like. Good luck.
Just my 0.02.
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Rob Channell
One Way Motorsports
1979 911SC mostly stock
1972 911T Targa now with a good 2.7
1990 Miata (cheap 'n easy)
1993 C1500 Silverado (parts getter)