DewsburyA
Far to late to worry about the cost - you are a commercial helicopter pilot and now a highly paid instructor. Ah watch those pennies roll in!!!!"!!
On the subject of Sloanes and the FI course there are a number of advantages / disadvantages: I dont think they are the cheapest by a long way. They tend to use 2 or 3 instructors (last couple of courses) one is MB. one is Military and the other is an airline pilot. This means you get a number of different styles which can be either useful or a pain depending on how you are feeling at the time.
I suggest you do your research talk to the providers and make sure you are able to get on with the person who is going to give you the training, its a lot of money to realise after a couple of hours that the next 6 weeks are going to be torture!!!!