Reasonable Print Shop for Art Prints

Looking to print 4inch X 4inch artwork, and blow them up to 6×6 or 8×8, near the Montrose/Upper Kirby/Galleria/Heights areas.

Any artists have any recs? I've been happy with Staples quality in the past, but haven't tried a Staples nearby and am hesitant. Not sure if a chain like AlphaGraphics is good, or if I should pay the premium and go with an actual art print shop.

Also, and cost estimates folks have had here in the past would be great – thank you!