Welcome from Ontario, Canada. It looks like this is your first post so I will assume you may not quilt? A t-shirt quilt is quite expensive to make if the shirts were ironed to fusible interfacing to prevent stretching. It is also about $150 to get it professionally quilted or more depending on the size.
If you intend to change shirts the quilting would need to be removed and redone which will add to the cost. If you have shirts you want in it, I would suggest turning the seam allowance under on the squares of t-shirt edges and just hand top stitch them over the ones there.