The Peavy/Samson they are asking $550 and the JBL set up she wants $500 I would like to keep the cost in the $700- $500 range.
I'll be the only one on this board to say go with the soundfactor+gig-rack setup for $500.
You're not going to be able to find 2 equally "usable" speakers and an amp for that much brand new (and you would still need stands, cables and some kind of mixer.) The Gigrack gives you mixer with multiple input microphone handling with reverb and monitors capability so you can actually use it for other Non-DJ types of events.
You may even be able to haggle them down.

I have a friend that DJ's and KJ's with exactly that rig and her mix always sounds good, fills the room fine and hasn't given her any problems. (she is careful and treats all her gear well)
She does nights at local bars and "day-job" is wedding/party DJ and her mix always fills the floor. (She hires for larger and outdoor events and I bring out even "older" gear than hers!)

You can dive right in now with that gear and as you grow can add/swap/upgade as you see fit.
Right now you just need clean basic amplification and I recommend your primary expenditures to be on your performance playback equipment and media -as well as learning to produce a clean high-quality output (that will translate to any amplification system or recorder)