you can ususally get the canvas one for $30 on Ebay
but if you want web sites... Here are a few.
http://www.atthefront.com/ Currently sold out
http://www.bayonetinc.com/german_field_gear.htm $39.95
http://www.edelweissmilitaria.com/ $60 but you get a sling
http://www.ima-usa.com/product_info.php/products_id/1283 $24.95
http://www.re-enactmentshop.com/p_wwii.htm 35 Euro, out of stock