I think trying to put perfective on the purpose clause here is to
attempt time travel, where my current action causes an
already-completed action. If you can say vIghro' vIje'meH Huch
vI'anmoHpu' to buy the cat I sacrificed money, and
you apparently can, then what exactly does adding perfective to
the purpose clause do? Maybe vIje'ta'meH means so that
I close the deal?
That's how I'd interpret it. If there had been a lot of haggling, or my credit card kept getting declined, and so I just decided to slam down some cash to get it over with, I think {vIje'ta'meH} would fit perfectly.