i had a crosman shipped over about 6 months ago no problems. In total ive bought 3, 2 from the USA and one from Canada. I had to pay a clearance fee for the 1377 and nothing for the 1389 or the 2289. Though i had to pay a clearance fee for parts i bought for the 1389 2 months back but overall no troubles.
If your worried have the valve shipped seperately as 'parts' and the rest of the gun shipped as a 'non-functioning air pistol' or as 'parts' again.
its worth it if you find a gem of a deal or a rare gun you've been after a while.
Danny
My collection = Ratworks BSA Scorpion T-10 .177, HW100KS .177 (tweaked by me), PP750, Crosman 1322 and 1377