The only problem for a newbie buying used is you may get a lemon. Another option is to buy a junk bike for $50 if you can, ride it into the ground and meanwhile educate yourself. Gel seats are not the best for a dedicated rider...you sink in and suffocate your pelvic blood flow. A firm seat where your "sit bones" (ischial tuberosities) carry your weight seems less comfortable but is better for your love life.