If you've owned this coop for less than 5 years, you'll take a beating on the sale. Also, based on everything I've read, appreciation will be long in coming. Rentals will have their own problems. First, what do the house rules say about subletting? How finite would the rental be? Will you have to pay 10% of the annual rent to the reserve fund of the bldg because you're renting your apartment? How involved is the rental process in your bldg? what fees are required? There is much to think about.
Coops were never good investment vehicles. If you don't need to sell now, don't. Good luck.
When it comes to Coop, there is NO average price in one zip code. It varies from block to block, Coop to Coop. Each situation is unique. If your Coop is closer to subway, very well maintained, steady maintenance fee, it should appreciate better than other Coops. Although that $300 rental fee could be concerning. However, I know most Coops in Rego Park. If I know your Coops name or address, I can give you a better opinion. Please e mail me at firstname.lastname@example.org or call me at 917-763-2260. Thanks. - Belal