Although people can recommend a shop to you that may have a DSTwo in stock, you can not request that an actual user sell you anything prior to reaching 100 posts and being able to see our trading section. Even then, requests for items from other users should go either in the WTB or WTT portions of the trading section. It's to lower scam risk. Hopefully you understand.
Last I knew, a legitimate shop did get a batch of DSTwo carts in stock for pretty much the regular new price. Whether they still have any is a mystery to me, as I don't recall which shop got them. I'm sure another user could help you in that respect.