Today I decided to get 2 spares for my M3 coupe, and ended up spending a little under what the OP spent. Discount Tire Direct, which is local for me, had 18" x 8" Drag DR-37 wheels in stock, that basically mimic my 360 Forged wheels. They are an 8 Mesh type design, with a matte black back, and machined face. These were $145/ea. I then bought the cheapest 245/40/18 tire I could get, which ended up being $86/ea!! These were some brand called Nankang NS-II's. I now have a pair of spare wheels and tires that will work for me or my wife's 335i. Here is a picture of the wheel...not bad. The cool part is, Discount Tire Direct will mount and balance for free when you buy a wheel/tire combo. Since they had them in stock, I ordered them this morning, and picked them up shortly after that.
The only downfall, is this is not very compact...at least not as much as the spare wheel combo the OP posted. These will have to sit in my garage when I am not using them. I needed them now, as 2 of my 360 Forged wheels are being re-done.
2008 M3 Sedan- Alpine White