Definitely boots first, spend as much as it takes to find the most comfortable ones. You are looking for a boot that you dont have to get super tight to eliminate heel lift. I like stiff boots, i tried Ride insano focus boa, k2 thraxis, salomon f22's and salomon malamutes, ended up with Ride RFL boots, they have a great internal lace and this strap that links to the outside lace that really locks you foot in, they start out pretty stiff, like an 8 and break in to about 7.
I really like my Blank snowboard, it is probably the best snowboard for less than 300 bucks and will be awesome compared to you rental. Im 5'10" 165 lbs and got the 151 white reverse camber, it feels a little small but is very easy to ride and is fun. If you are any bigger than me i would get the 157 though.
I suggest the rome united bindings, got them on my blank; they are a good match for the flex and can find no faults with them.
As for goggles the dragon DX have been my staple for a long time until i could get enough money for some spherical goggles. the DX's have always been solid, comfortable, the dont fog or scratch to easy and the replacemet lenses are super cheap.
that set up is probably about $600 bucks, spend the rest on lift tickets