Plug [Q] Busted USB port - worth fixing?

My USB port hasn't worked for a few months. It was intermittent at first, but by now it's just dead. I bought a battery charger and a second battery, and just swapped them every night. Works well enough, but it's a PITA.

I've had my i9100g for just shy of 2 years, so it's supposed to still be under warranty (here in Germany, anyway). I sent it to the repair facility but they're giving me grief about running CyanogenMod. Note that the phone won't even charge from fully off -- it's *clearly* a hardware issue, but I don't know if I'll be able to talk them into fixing it. Otherwise, they want over a hundred euro to fix the phone (they insist on a full motherboard replacement), which IMHO is barely worth that new at this point.

If I can't get it fixed under warranty, should I try to get the local repair shop to replace just the USB port, or should I try to replace the whole motherboard myself? (I'm comfortable with disassembling fiddly electronics, but I can't do tiny surface-mount soldering.) Have any of you done either of these things?