(Showing up late to the party as always!)
I actually started reading from the point that tpirfan28 (sorry, don't know your name) posted the rule change, and I'm seeing things from a few angles. I think parliboy and sodboy made the most valid points, esp. the former's point of this saving the show money in the case of products they still go out of pocket for. This seems less like a change on GP, as opposed to a change for the sake of the budget. However, ClockGameJohn referred to a reason for the change, and since Connecti-Matt's question, I haven't seen an answer...
And honestly, until I read Wikipedia and Brad Francini's page about 20 minutes ago, I had no idea about how the $500 offer even worked. Although the idea of a buy-in to see if you've won is very intriguing, I see no harm, nor foul in what's a minor rule change. Except for the prize levels, is it really any different than someone potentially taking home $7,500 on the first shot in Let 'Em Roll? Sorry, but when I'm staring down $4- or $5,000 in prizes I have no use for and could care less about what they cost, I'm taking the five Benjamins and preparing my wheel-spinning strategy.
And as big of a game show fan as I am, I would never would've recognized a difference were I not a member of this forum. I'm pretty sure Henrietta Homemaker will give two brown nuggets about it either.