I ordered a Nikon MC-DC2 Remote Shutter Release Cord. It says it will also work with the 7000. I haven't received it yet, but I'm sure it will be fine. I got it on eBay for $12.00. It's coming from China, but that's where they are made. They had it listed for $13.99 with a "make an offer" option, so I offered $10.00, they countered with $12.00 and free shipping and I said OK. Once it arrives I can let you know how it works.
I also have an ML-L3 from my Nikon D50, which also works with my D7100