Roland makes an incredible line of fully-weighted, 88-key digital pianos that sell for between $1,000 and $4,000. No, I don't work for Roland, but I have had students purchase these as "starter" instruments, and they're the closest thing to an accoustic that I've ever seen.
Another piece of advice I might offer would be to develop a relationship with a local piano retailer, and develop a cross-referral discount program. They can refer students to you, and in exchange you send them piano business. Offer each other discounts, and it's a win-win-win situation. I've been doing this for about 6 months now, and it's working gloriously.
Also, keep in touch with your local piano merchants. Any time there's a big sale, give your students the courtesy of a call to let them know!