Extracting Data From Inside Multiple Brackets

I'm trying to create an online order form using google forms. In my response spreadsheet I have an cell containing:

22" - Size 0 (£52.50),
24" - Size 2 (£60.00)

I desperately need to be able to extract the amounts within the brackets across to the next cell and in an ideal world add the amounts together. There could also be more than two sets of brackets, depending on the order being placed.

Is there a formula that can achieve this? All the ones I have tried will only extract from one set of brackets or will do both but then also include the string between the brackets too.