Any ideas for a cheap but modern headboard?

Use some frog tape (masking tape) and make a shape above the head of your bed--paint it a different color than your wall. Trim the edges with something that catches your eye--wood trim, beads,tile, etc. I made my own king headboard out of pine for about 50.00 and painted it. Lots of ideas to DIY headboards on Pinterest.

A piece of plywood, cover with foam and fabric of your choice.... you can fancy it up with buttons or upholstery nails.. hang from the wall on a cleat

Pinterest.com will have ideas and instructions for you

If you have a really large picture it can be placed on the wall above the frame ,box spring and mattress ..add risers under each leg of the frame which will raise the bed. Get some help since pic is soooo large and center. After adding pillows, etc. it really looks like a headboard!

There are many ways to make headboards that are budget friendly and modern looking:

Buy a piece of 3/4" plywood. Have the store cut it the same width as your bed and then by foam (by the roll) and fabric to cover the foam. You can add some quilt batting as well and use spray adhesive to glue the three pieces together. Then apply the entire "package" to the plywood and staple to the back of the plywood. You can mount the piece to the wall using a french cleat which is a board installed on the wall and one on the back of the headboard. This will take some pre-measuring so you install the headboard at the height you

Also, you might try search at thrift stores, you find just what you like or find one that you can modify to what you like.

You can usually buy a door at a thrift or salvage depot for less then $20, then paint it any color you like and hang it behind your bed

Use a piece of Masonite, cover with some batting and fabric, then staple the fabric to the back. To find inexpensive fabric, you can buy a flat sheet or curtain on clearance. Screw on to the wall so that the bottom edge is just below the top of the mattress.

A piece of plywood, some padding, some spray glue, brackets for the connection from frame to headboard or connecting it to the wall and you can pick a modern look (sheets are a great fabric to use, as well as drop cloth). I did mine like this years ago, and I still love it. I used half of a sheet of plywood, a roll of quilt batting, a can of spray glue to attach the batting to the wood, and I stapled the edges of a flat queen size sheet to it. You can go simple or fancy. It was supposed to be temporary, but, still going strong years later. Easy to change the fabric if you get tired of the look.

A painted door hung on the wall with a French Cleat, or you can pad a piece of plywood cut to size using spray adhesive on the foam and upholster it with fabric using a staple gun. Get even more creative and tuft it with buttons by pre-drilling holes in your pattern and use a plain button on the back side and use a 6" upholstry needle.

Here is a page for you to look over. You will see they're made of doors, wood on the wall, book shelves, surf boards etc. You will find ideas you love!