I was going to the spin class and loved it, I never bought the gel seat. It is true that at the begining my butt was so sore I could not sit for a few days, lol, but I got used to it and it never hurt again. I never bought cleats or special shoes. I just showed up with my towel, water bottle, a good heart-rate monitor watch and a positive attitude. I would burn approximately 700 calories or so per hour. The class got so popular and so good that it started to get too crowded and I hardly found a bike available. Plus my interest in cycling grew and took me to the road.
Both my husband and I bought road bikes, helmets, gloves and cycling shoes and take to the road a few times a week. I started slow and short trips, now we bike 20-mile trips twice a week, at about 1100 calories. I love it, it is different than the spin class, but if you cant do the road bike, stick to the spin class, it is a lot of hard work but it is a blast. Try to stick to it at least 3 times a week rain or shine. Good luck!