When my husband and I met, I had a metal framed bed that I'd gotten from Walmart or some such place, and my husband bent it during a session of adult things. When we moved in together, we got a real wood one, possibly plywood, from Amazon and have moved to 3 different homes since then. It has held up very well.

Estate sales have elderly person furniture that's enormous and ornate and Amish furniture is also rather large and quite expensive. If you want something in the minimal or modern or contemporary design styles, just look for anything that's real wood. MDF is code for particle board, so avoid that.