Not sure if you've made a move yet (since this post is almost one week old), but $23k is a good deal based on the info I've seen. I have an online subscription to Consumer Reports and they have a car pricing/buying service based on TrueCar. I used a Boston zip code and equipped the car you describe and came up with the following-
CR "Program Estimate" - $23,543 (including $1,500 Customer Cash and $500 Owner Loyalty Cash)
The Edmunds.com True Market Value price is $24,209 (minus the $500 Owner Loyalty making it $23,709).
So either way, $23k sounds like a very good price. As long as they don't charge excessive/bogus fees at the dealer, it sounds like you're getting a solid deal!
I've been shopping for almost the same exact car. The only difference is that I want the Eternal Blue Mica and Automatic Transmission. I hate to admit the latter, but a hip and ankle fracture a few years ago have made it a necessity for my 70-mile daily commute.
And it appears that you and I are replacing the same exact car! I have a 2006 Mazda3 s Touring 5-door (5-speed manual) and it's Titanium Gray. I bought it new in 12/2005 and it is still a great car. I'm planning to hang onto mine and drive it one or two days per week. I have a very strong sentimental attachment (and it only has 110k miles on it).....
Right now, the challenge is actually locating the car I want. I've found more than a dozen in my color with the Premium Equipment Package, but they all have the Parchment interior. That's a deal-breaker for me. I found one with Black interior about 450 miles away, but it has the i-ACTIVESENSE Safety Package and i-ELOOP Package. That's $2k in features that I don't want, so again, a deal-breaker. I suppose I'll be waiting for one that I want to show up sooner or later.
BTW, I liked the old days when you could get a Mazda3 with any interior color...as long as it was Black!