where can i buy a toddler bed mattress, length 175?!

[ilikeyoursleeves]

i can't find one anywhere! they are either 140cm or 200cm grrrrrrrrrrrrrrr...

I've just found here. They make them to any size apparently. There are probably similar sites you could try too.

Ikea do extendable beds. We have one where each end can fold up or down, with one end down I'd bet it would be the size you're looking for.

Have you looked on Ebay?