FOLLY: 1415 at Eko Signature, without any hesistation is what first came to mind when I read your question. It's not a place you go everyday and the food is one the best I've ever had in Lagos. Izanagi would also be nice too. Ps. Nice on meeting your target!
NOSA: I've never been to Talindo Steakhouse, please do it for me. Let me live vicariously through you.
NOSA: You're never to find a "cheap" steak that's worth it. Not in Nigeria. Not anywhere. If the steak is cheap, it's probably shit. #FreeGoodAdvice
FOLLY: Yeah, Bottle's is definitely not what comes to mind when I'm thinking about steaks in Lagos since their specialty is Mexican. I'd recommend RSVP and 1415. You'd pay a pretty penny as either of those places though
FOLLY: You're cute and like me, I love planning things like this way in advance. I always start thinking about options way too early. I like La Taverna because it's nice and very affordable, they also have a good wine list. Ps. their house wine isn't rubbish like at most places, so you can just get two glasses of house white/red so as to save on a bottle.
NOSA: If Winehouse had decent food, they'd be perfect for this. Alas, they don't so i'm with Folly, go to La Taverna.