One way to find out would be to try the following searches and see if you can find some similar items by those artists. That should give you an approximate idea as to what they could be worth. However, if you would want a definitive answer for some reason, then I would suggest taking them to an art museum, a fine art dealer or to an auctioneer who has some specialty in auctioning art.
You will find some prices listed for the work of either of those artists via clicking on the search at the top. The bottom search is an image search. You might want to click on it to see if any similar works appear and then click on the images of the works that you find.
Ming Feng Donny Finley Art - Google Search
Ming Feng Donny Finley Art - Google Image Search
