Informix Licensing Issue

We are a small development company and we develop financial application based on Informix database. Our client runs various version of Informix databases. In order to support our clients, it is necessary for us to maintain various version of Informix databases in our development environment. While discussing with Informix Corporation, Informix said that we have to have license for each version of Informix over all the platforms and that cost is too high. At present we are running Informix 9.21 but to support our client we need Informix 7.30, 7.31 and 9.20 and all these databases we need in multi platform ( Sun, HPUX, AIX and Dec OSF1). If you are similar like us then I would like to request you what licensing you are following to get benefit in development environment. I would like to appreciate you if you could give me your suggestions. Thanks Sent via Deja.com http://www.deja.com/