George7941, I don't use the spikes on my current STI(4WD) because they don't fit the 17" rims. They did fit the WRX(4WD) and the Camry(FWD) that we originally bought them for. Our Tundra is 4WD and has a set of BFG TA's on it and does just fine in the snow without chains or studs. IMHO, Spikes are ALMOST as good as a dedicated set of studded snow tires for occasional use. If you need them once in a while the Spikes are the way to go. If you need them for weeks, or months at a time, go with snow tires. I used the Spikes on our Camry when we lived in Maine--my wife did her physician's residency in Bangor.
A dealer unwind is essentially a car that was purchased with financing, the financing fell through and the dealer had to take it back. The dealer then can't sell the car as new. They typically have less than 1,000 miles on them. They typically sell for about 20% under invoice, but you have to pay cash or have your own financing. You can find them by calling a dealership's general manager and asking about them. For example, when I was looking for an STI I called every Subie dealer within 200 miles every Wednesday morning to ask. Some dealers didn't want to mess with me (so I called salesmen), others were more than happy to speak with me as a potential customer.
If you look for an unwind please have it inspected. Some dealers (not all) will try and sell a wrecked car that has been patched up.