The foam is something you can do yourself quite easily - I did my AE1 with some stuff I got from here - frankly, I think you could find similar foam sticky backtape in a hardware sotre... It works well, but its not the same stuff that came from the factory, and frankly, it is just a bunch of foam tape you trim yourself... I have mixed emotions on the subject - no problems with the comapany, I just wonder if its not something you can do more cheaply with a little research.
Word of caution - use compressed air to clean the focusing screen only - the matt surface is very delicate and it is easy to make it worse than it was - guess who learned that the hard way... If the stains are on the prism itself, you may want to invest in a CLA from a pro. Its a touch expensive with these old 35mm bodies... since they have becme so inexpensive it often costs more to perform even the most basic service than to buy another one. But if you like a camera, and it does good work for you and it has a value more than the monetary one, it is sure worth it.
Another option - depending on how "mechanically" inclined you are - is to search the web for a repair manual - this one you have to buy, you may find a freebie somewhere like this - not sure of the quality, but its another option.