A very sturdy Inclined bed frame.
This bed was made by John Bresnik, to a five degree head up angle, from planed pine.
This timber is inexpensive and available from sawmills and DIY / Builders merchants stores. The small foot board is raised slightly just to retain the mattress and sit's below the level of the mattress.
The legs are upright and the side rails screwed and glued to the sides at the desired angle.
The slats are also pine.
You really don't need to spend much money to incline your bed.