You would almost be better off just ordering it online than trying to amass all the ingredients to make a blend of it yourself - which would cost an arm and a leg if you don't have them all on hand already. Even then I would be a bit skeptical how close it would come to the real thing since there are so many ingredients in it, and so many opportunities to not get the ratios of each correct.
I like Old Bay, but only in small amounts, and only on occasion. It's not a seasoning blend that i use regularly because it has too distinct of a taste to it, and it makes everything I am cooking it in start to all taste the same.
One of the more interesting uses for it, was in a buffalo wing sauce along with some fresh lemon juice, and the usual hot sauce and butter. It added a really nice depth of flavor and the lemon complimented it all very nicely.
