This websites classifieds contain both new and used items.
Used items are not always poorer quality, in fact many used items can already come upgraded or have had known issues repaired by the previous owner.
With the budget you have set I am curious if you remembered to factor in the cost of additional magazines, batteries and BBs
On the topic of craigslist I would be wary. As it seems you some what lacking in knowledge someone could capitalize on the situation and pull a fast one on you. Unless you can physically meet with the seller and inspect the item I would be wary with any craigslist transactions.
In the mean time please take some time to review some of the threads in the frequently asked questions section as it contains many threads on topics that will prove useful to you.