You have a challenge on your hands for a couple of reasons. The first is the economic straits your government and most municipal governments are dealing with and the fact that money has not been allocated for this service.
The second is that you have identified a service that you believe will be beneficial to your citizens, instead of your citizens coming to you asking for this service. Therefore the cost to benefit isn’t only going to be questioned by administrators, but also potentially by citizens who may not understand the use or need for it.
The first obvious question to ask yourself (and you have probably already done so) is “why is this service important to provide?” This question can be further examined by determining what specific data you want to offer citizens. Data can be diverse. Some of it is easy to obtain, while other data will require more time for retrieval and analysis meaning higher cost.
Can you prioritize the data to determine which is most important? That way, you may be able to determine what resources will be needed to provide it. You probably have already gone through this exercise and determined the answer after asking yourself what segments of the public are most likely to benefit from the data? Again, is there a favorable cost-to-benefit ratio to retrieve and provide certain data sets? If so, now ask yourself the biggest question: “Can we get somebody else to pay (us) to provide the information?”
Look to the business community. If it’s data of economic significance, then the chamber or real estate communities may find value and believe it is worth acquiring or gaining access to it.
Theoretically, you may have identified data that you believe is important to citizens, but have not found a way to fund it and then have another, lower priority data set, but have an external source of funds to provide it. That should not be a hard decision to make at this time. Providing the lower priority data may provide a pilot for the public and for government that there is benefit in open data and gain internal and external support to get funding in next year’s budget or by developing a user fee arrangement. Good luck.