Miss Manners: What’s the polite way to invite someone when they need to buy their own ticket?

Dear Miss Manners: How do you extend an invitation to someone to do something together if you’re not offering to pay for them? Say a concert or play is coming up, and you know someone who would like to go. Of course, you would like to sit together.

Is it polite to say, “Hey, that band you like is coming here in June. Tickets are (dollar amount). Would you rather grab your own ticket, or should I grab yours when I get ours so we can sit together?”