The 430 will rust much more quickly than the 304. For $14 more, I'd go with 304.
That's possible. In my view though, it's worth it to spend the extra $14 for the higher quality steel.
I just added a set of flavorizer bars and grates to my cart on ebay and the shipping came to almost $36. Does he not combine shipping?
I've shipped large 50-60lb boxes of beer across the country dozens of times and never paid more than $30 for that.