I have just about come to the end of a tube of loctite 248 bought probably 18 months ago for a one off job and at the time i was begrudging paying £7 for it (well its £7 now!)
Halfrauds (not sure on the in store price) is cheapest place i have seen it!
works great works on stainless and comes in handy prtitt stick type tube that means if you only use a bit each time you dont waste the tube. Performance wise it seems to have been up to the task. In a marine environment its double useful as it stops things working loose and also seals the threads stopping ingress of water.