If the house next door is a mate and friendly, then I'd be inclined to buy a long Cat5 cable and run it to your place. If it won't reach that far, is there an outbuilding where you can attach a Wireless access device to a Cat 5 cable from his router?
I live in a long thin house, with a workshop some way off from one end. I had all kinds of problems till I bought a separate WAP and put it at the "other end" of the house from the main wireless modem router. I now have full coverage all over the house, workshop, and garden.