Hey mate, at Peakmonsters you can place bids, this is not something that you can do on the official game site.
And as you can see on the picture, you have also the option to set bids for rentals.
Regarding payment, you have the option to pay in DEC or credits. Credits is basically the FIAT money (dollars or Euros) that you put into the game. You know how to do it?
Let me know if you need support.