
Ok, what about an option for a second pet shop? The current pet shop has pets available at levels 30, 40, 125, 250, and 360. I was originally more along the lines of alternate pets and not necessarily upgrades, but there could be a number of variations too.
Something like level 50 gets glowing spider options, or toss in some ranged options even like 150 gets warlock options. The current pet shop pets are weaker than what you could purchase for real money at your level (with the exception of boss dragons at 360), so nothing would be overpowered. There could always be options for higher levels as well.
The world of FT has expanded since the original pet shop came out. That is true for size as well as more monster options.