There are a couple of threads on here that discuss the subject of draw knives already, you may want to do a little search. I picked up a couple vintage ones at an antique store -- very heavy duty -- good steel!
As Rad suggested you may want to look at flea markets or use tool stores. You can offend fine them I pretty good shape. A good new one will run from $ 50 to $100 depending on size and shape. I have a Flexcut draw knife I use for stripping bark. It is about 6 years old and does a good job. I also have a heavy 12inch draw knife that was my grandfathers. For sticks I much prefer the Flexcut. The Flexcut run from $40 to $50 and are carried by most wood carving sites or stores.Pfiel Swiss Made sells a nice small draw knife it is about $80 and sold by Woodcraft who also has the Flexcut tools.
These are some suppliers I use and have had good service from.
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