I have found that as long as the hides fit the snake, the overall cage size does not matter as long as they cannot escape. Depending on what you are looking for you can sometimes get better deals on babies/yearlings. Not sure where you were planning to buy from but if you buy a baby/yearling from a breeder you have a better chance of getting a healthy animal than you do from buying an adult off craigslist. An unhealthy animal can be difficult to spot to an inexperienced person and can cost a great deal in money and frustration.