i did a microchipping course a couple of years ago as was running a dog business and wanted to add mobile microchipping to my services. the course itself is good although i did find it a little too easy and drawn out but i guess that was just me as some of the other people on the course still managed to cock up the procedure Doh! (numpties most of em).
the cost of the course is ok but then you have the kit to buy and the price of the chips themselves is expensive and can only be ordered in large quantities not too bad if you have a buddy and you club together to use buying power to get the discounts on the larger quantities.
saying that i never have to pay to chip any of our dogs or cats but if its for only doing your own stock unless your a dog/cat breeder its hard to re-coup the costs.
mobile microchipping is the way to go especially if the government makes chipping compulsory however the cost of chipping will come down i know pets at home were doing chipping for £10 when getting puppies vaccinated so i was forced to compete with that as i was mobile i was charging £15 a time. profit was negligable.
best way forward if you did it would be to arrange chipping parties offering a discount for 5 or more dogs at a time.
hope this helps