TD Ameritrade does not list their mutual funds on their public website. The website does not mention any proprietary funds, so they may not offer their own funds. If you log in and limit your search to NTF (No Transaction Fee) funds, you should be able to find out which index funds are available through them. If that does not work, call them and ask what low cost index funds are available with NTF.
If you are saving for a specific date and purpose under two years, the stock market is not appropriate because of risk. If you can defer the intended purchase because the market has a bad couple of years, you could invest. Generally, things like vacations have a schedule, and if you need the money to be there at a specific date, go for a less volatile alternative.