UMD Honors is full of students just like you. Many got into Chicago/Brown/JHU/Favorite-Name-Here but couldn’t justify the costs. There will be plenty of high achieving students in your classes. If you can’t find intellectual stimulation at UMD it will because you didn’t look very hard for it.
Run the numbers here: http://www.finaid.org/calculators/awardletteradvanced.phtml and talk them over with your parents.
And read through this thread to find out how you could do what you want to do at a place that isn’t nearly as “top-notch” as UMD: http://talk.collegeconfidential.com/parents-forum/905843-top-student-at-a-3rd-tier-school-four-years-later-p1.html