Prices do change, but having a rough idea is always good. I wrote a script for uortrade where you can check various prices, there's more detail here (including a full list of the results, look for the zookeeper section for prices per animal) http://uorforum.com/threads/pc-on-uortrade-price-check-script.27158/#post-266138 The prices are based on trade forum sales, #uortrade and player feedback. You might get more or less than this depending on demand, but these at least reflect previous, recent sales.
There used to be something like this when I joined, and it was really handy when you've not followed the market. That player left so I thought I'd create something to help. If you ever find that a price is wildly off, give me a message so I can fix it for others in the future
yes it really fluxuates. ive sold king scorpions for 5k, all the way to 20k. ive sold majestic harts for 15-25k ive sold crimson drake for 30k, and 75k it's really just about what people need at the time, and how bad they want to finish their scroll. though i noticed that the following seem to consistently sell over 100k: - silverback gorilla - savage ostard - raging grizzly bear there are a few more that are consistently 80k+ but i can't remember them all.