Ha, good luck!!!
On a serious note, I have some very recent painful experience with shipping from Banjul. We rode two bikes down to Banjul over Christmas 06, safe and confident in the knowledge that we could fly them back with Redcoat Express, which a number of other posters had previously successfully used with minimal hassle.
When we arrived in Banjul we discovered that Redcoat will now no longer take motorbikes as they need a dangerous goods certificate. We tried a few other airlines with no success, so resorted to shipping them out in a shared container with OT Africa, through Gambia Shipping Agencies.
Well needless to say, the bikes arrived back in the UK last Friday, six months after they were placed in storage in Banjul. It would be quicker if you took the entire container (approx UK£1,000), but as we elected for a shared container (approx £180 per bike), we had to wait until the whole container filled up. Despite the delay OT Africa were fine to deal with and generally helpful, although it was difficult to get a firm answer as to the exact shipment date. I dealt with Fanta Conta. her contact details are:
Gambia Shipping Agencies Ltd
1A Cotton Street, Banjul, The Gambia
Tel: +220 4227518
Fax: +220 4227929
Mobile: +220 9918166
Good luck and be patient!