I done this exact thing because my paypal was not working i sent off some postal orders & got totally ripped off, i paid on the beginning of august opened a dispute with ebay & because it was to sperate things i brought which came to £26 for both & neither was over £15 i can not make a claim....
I think ebay is crap these days & i also think paypal is, you are not covered at all & people know this, they are just ripping people off left,right & centre in the last 6 weeks i have lost £26 & am now having to open another dispute for £27 it's ridiculous.
There is nothing you can do though, did you send the postal orders recorded delivery or do you have proof of posting?
I have filled in a p58 form & sent it away to find out if the postal orders have been cashed but not much else i can do apart from sit back & let someone take my money.