Do NOT buy a mask mail-order without trying it on. Fit is the most important thing, not price or features. A leaking mask ensures you won't have a fun time during class or diving. If you're certifying locally that cold water hitting your face can be a shock also. I've never paid over $80 for a mask at any local dive shop and usually around $50 or less. Some extra cost features will be softer skirts for a better fit or frameless features - also for a better fit. Adjustable strap buckles are something I dismissed as useless till my last mask, now I really like it. I find that by changing the orientation slightly downward, the mask stays dry better.
Any $20-30 snorkel will work. Your dealer should have them. A smooth bore is probably easier to use. For probably double the price there are some folding ones that you can buy. My last folding one dry-rotted from non-use.
A good pair of paddle fins is well under $100. Besides the ones mentioned in the previous post, others to ask about are the Oceanic Viper or Vortex or the Mares Avanti Quattro Pro. Stay away from anything with flex hinges or power bands or other special features because what they mostly do is break sooner than a standard solid blade fin.
Your dealer may also show you split-fins as an option - they're more efficient (easier to kick) than paddle fins for reef touring but in tight places are much less maneuverable - for example they're almost impossible to back up in. The reason they're more expensive is not that they're better but that all the mfr's have to pay a patent fee to sell them.
Spring straps are a good upgrade as you'll never break one. The ones with an integrated handle are often easier to don/doff as long as it's pretty substantial looking (most will be).
Boots should be $25 or so. Really good boots are $50-60. I wouldn't skimp there since you may use them for a while. You'll probably be interested in thicker boots for MN water - like 7MM. Try on the boots with the fins you plan to buy.
In MN I wouldn't be surprised if they recommend a good pair of gloves also. 5MM might be a good choice for all but the coldest water. 7MM might be better but they're stiffer so hard to grasp/turn small things with.
