The components required for an amplifier would be just a couple of dollars - an LM324 opamp and a few peripherals which could be assembled on a proto shield. This last would be the most expensive item. If you just want some crude relative readout, you may get by without them but, in that event, you may be better off with a cheapo thermistor.
I have managed to leave my PT100s on the shelf. The link I posted should have all you need.