My husband does not own a sportscoat either. He is so big that one does not fit him in the shoulders and arms. He does not wear a suit or jacket for work, so it is not feasable to have one tailored for him. He changes sizes so much as well. Might I suggest checking out a thrift store? My BIL needed a suit for a funeral and they have no money so he found one at at thrift store and looked very nice. I have eaten in many fine restaurants and think it is silly for a restaurant to require jackets to remain on and such. I eat gourmet in my pjs sometimes and it might even taste better that way. V&A is going for that old school charm, though and it kind of fits in the theme. You might be more comfortable in another restaurant. I like more hip, trendier restaurants myself. Do not stress on a sports coat for a nice dinner. Chances are if he does not have one, he will be uncomfortable. Just enjoy each other and a nice meal. You see, i have given up on my husband years ago!!
You also might want to look at TJ Maxx, marshalls, SYMS, Value City, Ross or K&G. Maybe even EBAY.