I have several scanners, all Uniden, including a BCD396T and a BCD996T.
I have used the various ARC programs extensively in the past. I have found the programs to be a bit quirky, though they are full-featured and Gommert's technical support is usually very good. There are several ARC-related Yahoo Groups where Gommert supports his programs, though I don't know if there is one for ARC500. Lately, I've been experimenting with ProScan, but the author is not talking about supporting the GRE scanners at this time.
When I tested a GRE PSR-600 last summer, I tried all of the available PSR-500/600 programs. I ended up using ARC500. However, I only kept that scanner for about a month before trading it.
One other item Brownsburg PD...They are still using their old VHF frequency, 155.535 MHz, as a simplex talk-around channel. You may want to program that as a conventional object in your scanner.
One other thing about scanning Project SAFE-T in the Brownsburg area. My experience is that there are places around town where reception is difficult. The area around 56th and Northfield and near the high school, where I used to live, seem particularly bad. My new house is closer to the SAFE-T tower just north of Danville and I get much better reception than I did at my old house.
As for ebay, the price you see things sell for there has more to do with what someone is willing to pay and less to do with what the item is really worth. As a buyer, I get very frustrated when I see prices going through the roof. But, as a seller, I'm tickled pink.