You have an interesting product and a great sales pitch. Why wouldn't I be willing to absorb your cost when paying with a foreign drawn check as a client? I might if I really wanted the product and had no other means to pay for it.
Do those that pay by check create an online order first and choose, "pay with money order or check" in a checkout dropdown box. Or do they just send some token amount without even realizing the shipping charges?
If they are creating an order then you can add additonal charges based on the payment type, while explaing the cost of check handling in a hint box beside the type of payment.
Having run an online business for 7 years I really really try hard to keep it totally mechanised and try not to let small additional business turn into large additional work. ( If you have been there I apologise for the lecture, if you haven't I offer it as a grain of wisdom) Matching up orders to small checks or folks who want to use PAYPAL is not somewhere I want to go.
These are folks who don't read the warnings but have put their faith in us and have usually run up an order and then printed it out and put the whole lot in the mail.
I should keep my thick skin on and shred em but I keep thinking that some new system or imaginative bank somewhere might have done the decent thing and... hey wait a minute, a bank doing the decent thing! What am I thinking of.....I think I just answered my own daft question, snafu in the banking system.
"... usually run up an order and then printed it out and put the whole lot in the mail. ..."
On my cart the only way to get a complete order confirmation for print is to complete each step successfully including the payment option. So by having a check option that they can choose online allows your cart to add an additional $15 US for foreign check (based on address) to the order total for handling as well as append an explanation on the order confirmation for printout.
Those that don't provide the correct ammount simply do as you do now... cancel.
Get a US Dollar account from your local bank - all the major ones offer them to their business clients. You can pay the checks into that account and then transfer funds into your main GBP account once you have accumulated a reasonable amount. Dependent on the bank charges and the volume of checks received, you may find that it is worthwhile.
I've heard auctionchex mentioned a lot on the eBay forums (uk). I think either the owner, or some one posts a lot on their when people ask similar questions (i opened this thread with the intention of informing you of their presence).
I have now had some correspondence with these guys, they are a bureau de change so you endorse your check and they clear it into their own accounts and send you ( or transfer electronically) the sterling or euro equivalent.
This route doesn't give you the same cover as using a bank but for a few hundred bucks here and there I can live with that exposure.