Unlike warranty repairs, which can only be done by an Acura dealer, routine maintenance can be done by anyone, including dealers of any make of car, as well as independent mechanics. In general, independent mechanics tend to be less expensive than dealers, since their hourly labor rates are less, and independents typically charge actual time, which is often less than the book time that dealers charge. However, there are exceptions (since prices are negotiable, and also dealers sometimes run specials).
As Bill notes, I would be wary about huge differences in price, and I would make sure that they are both doing exactly the same services. $259 vs $350, it could be a difference in rates or a promotional special. $145, sounds like they're skipping some services. But if they're doing the exact same things, go for it!
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