The first question you have to ask yourself is "do I really want to commit all this money to a sport that I don't know if I like?". If you don't know the answer to that question yet, then it might be wise to rent boards for a while (I know they suck, but it doesn't matter that much when you're starting out).
If you really do want to dive in headfirst, then you should be comfortable with spending 200-300$ + for the board, 100-200$ for boots and 100-200$ for bindings. Once again, that's if you really want to get a complete set that you will use for a long time (personal advice: go to a used sports shop and buy an old setup, purchase better stuff when you know you want to).
On to gear (take what I say with a grain of salt for I am just a humble enthusiast, not a pro recomender like Nivek or BA).
Boards: Size-wise, you're on the right track with 145 range, and I apologize if this comes off offensively, but are you going to grow at all more? If so, then you may wish to look at a longer length (i.e. 150 range) because that would suit you more at a heavier weight (board size is primarily weight based). Your foot size being 10, you don't need to look at wide boards. Only at the 11.5- 12 (men's) US size should you start thinking about that. There are many beginner boards that are perfectly usable when you have a higher skill level like the Brigade Snowboard | Snowboards | K2 Snowboarding 2013-2014
. It comes in a 147 which is in your current range, and is 300$. You will probably want either a beginner board (cheaper, ok for park), a Freestyle board (park/ jumps) or (and I recomend) an all mountain board (midle of the road stiffness, good for all types or riding).
You may be interested in learning about camber and rocker profiles which are one of the key factors in affecting how a snowboard "rides". This write-up by Wiredsport Rocker, Camber, and Everything In Between
is pretty great at explaining it, but basically it's the curve of the board (imagine arc-shaped or U-shaped or a mixture of the 2) and that makes a giant difference along with other factors (I.e shape, length, stiffness etc.). (IGNORE THIS IF YOU LIKE)
Going to your local snow sports store (NOT SPORTS EXPERTS, SPORTCHECK, SPORTS CHALET etc) but a more concentrated place will have staff that can explain all of this to you and are generally enthusiastic.
Bindings: some say are the least important part of your setup, but choosing the right one is important. You will need to go for a medium-large or large- extra large depending on the bulkiness of your boots. Be careful of what purpose bindings that you are buying. There are many different types of binding stiffness and other feature which could make you hate a pair that another person using their setup for a different purpose would love. Generally, the types that companies advertise their bindings for are: rails/park (very flexible) freestyle (still pretty flexible, pretty much park but for jumps too) All mountain (medium flex, maybe what you're looking for if you don't know what style you want yet?) and free ride (very stiff, meant for carving and going fast/powder) an example of bindings you might look at would be like: Burton Custom Snowboard Bindings 2014 | evo
Boots: you will have a bad time if you don't like your boots. Just like with running shoes, TRY THEM ON BEFORE YOU BUY THEM. Try as many as you can, ignore the exasperated looks the clerks give you, try as many as possible until you find "the one". Like bindings, they are made for specific purposes so pick the type with the flexibility for your intended riding focus. There are many fancy technologies that you can go for, like boa lacing system (no laces, more of a crank with a wire, much faster than tying your boots up), but none of them are essential. Go with what fits.
All in all, if you are on a limited budget, rent or buy a used set, it doesn't really matter when you're learning, just have fun and maybe save some money from the equipment for passes.
Sorry if that was a lot of text, I sort of enjoyed typing this
Also, talk to the store clerk at a smaller store. they probably know more than I do.