Probably the most difficult thing (after the cool fuse pliers - there are two styles by the way, one with the little spring balls in the interior of the handle and one just like a regular set of pliers - both in plastic, and the wood handle for the screw driver) is to get a proper bag, as these were specific to the 113 (and the 111/112 I think)
The water pump pliers can be ordered from Samstag (and they even have the MB star), the wrenches, regular pliers, wheel mounting peg, lug wrench and spark plug wrench were common across all the product lines and are reasonably easy to find on ebay or similar, just need a little patience. Samstag used to have the small box of fuses (with the 25Ω stubby fuses). I had to complete my tool kit some years back and got 'em all.
I have seen the plastic fuse pliers on ebay for around $75, but that has probably been six months ago.