Can I replace my 650c wheels with a more standard size? I have a Bianchi eros with 650c wheels. My back wheel was driven into and is now buckled and I am finding it very difficult to replace it without spending hundreds of pounds. 

Is there another wheel size that I can use instead of the 650c that will fit on this frame? Or is there a manufacturer that I have overlooked that still makes 650c wheels for an affordable price.
The answer is yes, but it might not be cost effective for your situation. I will answer this question from the perspective of someone who already owns a 650c frame but wants to purchase a new wheel-set. 

The BSD of a modern 26" mountain bike wheel is 559mm, which is only slightly less than a 650c at 571mm. Sheldon Brown provides a big table. If your brakes can accommodate an additional drop of 6mm (calculated by (571mm - 559mm) / 2) then you can use a 26" wheelset in your 650c frame. 

This has been documented by restoringvintagebicycles.com; they have also successfully run 650b wheels in a 700c frame. 

So why might you want to do this?


Wider selection of rims
Wider selection of tyres
Wider availability of parts for long tours in remote places
Increased tyre clearance allowing for larger volume tyres
Reduced toe overlap