The TSU3000, which is almost identical to the 3500, with the major difference being more memory, can be had on e-bay for less than $100. The TSU7000 can be yours for less than $300. Again the main difference between the TSU7000 and the 7500 is the amount of memory. I have both a 3000 and a 7000 with 20+ devices programmed into them, and haven't even come close to using all the memory.

To make a long story short, buy one of the above ASAP. To paraphrase the great Warren Miller. If you don't buy a Pronto NG this year, you'll just be one year older when you finally do.