When I had this problem I attempted to train Alex (my dog) not to bark. Tried manually myself but needed more help. My neighbour and I chipped in together to order a bark collar. Its true that they can be quite expensive but it solved our problem after about a month of training. I used the Master Plus Pro collar which I purchased online.

The collar only sprayed (I dont beleive in static attacks!). A while after trainging a simple warning noise from the collar was enough to deter him from barking.

Think I paid about £120 for my collar but have noticed it has now came down in price...