starting problem -- Please HELP!!

My girlfriend's 1999 neon is having an issue starting, I tried to start it about a week and a half ago and all I got was a clicking sound. I went to the local parts place (they tested it as bad) and $189.00 later replaced the starter (with $80.00 core). After installing the new starter the car fired up on the first try. Now six days later with the new starter, I get the same click sound I had before and the car won't start. Please help, it is killing me.
I did install an aftermarket radio and speakers a few weeks ago, using a wiring kit for the neon. I have no amp or anything like that. Could this have an effect on the starter??
The battery will play the radio when I turn the car on, I just get clicking from the celenoid. Could this be a bad battery?? Thanks for any help.

mooree

Could be the battery, or maybe a broken or lose power cable.

Well.....it was the battery. I decided to jump it with my jeep and it fired on the first try. I took the car down to the auto parts place and had them check the charging system in the car and it seems like the battery just went dead.....???? Thanks for the reply.

i think you should consider checking your alternator or wires to your starter.

definately check out your alternator, something isnt right there. :uhoh: