I recently upgraded my iPhone 4 to a 5 and while I have never had reception problems I was stunned at how much faster it was going from the 3G to the 4G/LTE.
If you are worried about price I would recommend you check with Best Buy. When I upgraded they were having an iPhone trade-in special in which they were swapping old phones for the 16G iPhone5. I paid nothing at Best Buy for the phone but my next AT&T bill was $36 more for the new contract fee. It was a limited time offer but they said they do it periodically so they might run it again.
And my Girls.....
Dallas - ACD mix, 9 yrs
Willow - GSD, 3 yrs, CGC