I also have a '98 M3 which I plan on driving until the E92 M3 is available. I love my car, it's faster (with very minimal mods) than any E46 I ran against last year at Watkin's Glen, including on the uphill long back stretch which is a total test of horsepower. It's significantly lighter, and fun to drive. Why don't you keep your E36 and just buildup your down payment instead of buying a car to tide you over until the E92 arrives. A newer car which will depreciate more over the next year or so than the E36 you already own.
That's my $.02.
Yeah I am keeping my E36 M no matter what I buy and I wont be making any purchases for another year. I am beginning to lean in the direction of a used 997....