Don't worry about finishing research and conservation if you zoo is low on funds. You can stop all the reasearch/conservation, and leave the computer on for a while (Periodically checking to make sure the guests are happy, animals, etc)
Then when you come back, you can start up the research/conservation. And you know you can filter through the stuff.
For example, if you don't want to research "Swinging log toy," since you want snowy cave, you can uncheck the "animal enrichment" and only put a check next to animal shelters. Just thought I'd let you know in case you didn't before. If you don't do this, you will have a lot of stuff to pay for that you don't even want! =)