Seashell is correct, you certainly don't have to spend a lot on a mask to get one that will work for you. Especially for a snorkel mask (which doesn't have to be tempered glass like scuba, tho most are depending on pricepoint). Key thing as mentioned above if fit. if it fits and seals well, and is comfortable, it's the one you want. I've found $25 masks that will work WAY better than a $100 mask, becuase it fits a face. I don't even look at the price, and advise my students the same when mask shopping. Try them all for fit, find the best one, and then look at price.
Again as mentioned above, best way barring the pool or 'toilet test' is to place the strap in front of the mask, slightly press the mask to your face, and inhale to create negative pressure inside the mask. Then hold your breath (do NOT continue to inhale), lean forward, and see if the mask comes free from your face. A proper fitting mask should hold the seal.
Snorkels - trend in the industry lately is to add a 'new' gizmo to snorkles every model that comes out it seems. Dry, water funnels, flappers, purges, ect., ect..... musch of these are simply what you get used to and are comfortable with. There isn't anything wrong with an inexpensive standard open tube snorkel. Nothing wrong with one with gizmos either...except that the more bells and whistles, the more to break or malfunction (my opinion). Again, get one that is comfortable in your mouth, and that the tube isn't over-large in diameter or lenght (creating dead airspaces leading to CO2 buildup). Most standard brands will have an acceptable size tube.
Last thing on masks, rsarceno mentioned using toothpaste before using. Good advice, but I'll add that you not only have to apply it, but 'rub' it into the glass. I normally have students do this at least a half dozen times with a brand new mask. The manufacturers spray them with a protective coating (the lenses). This coating will cause rapid fogging unless removed. Toothpaste (most kinds, especially the old fashioned 'paste' rather than gel) contains abrasive material that will gentle scrub off this coating. I've also known people who have had good luck with the product Soft Scrub, a kitchen cleanser. Any mild abrasive will work.
Hope that helps!
~ MJ