Best place to buy non-warped door casing ?

Softwood door casings - all the ones in B&Q or Wickes (I opened lots of packets) were warped, twisted or otherwise misshapen. Not tryed the BMs yet, but, where is the best place to reliably get planed softwood stuff that is, um, straight. The old door casings in my house (1930s) are held by 2 nails each side, and are as plumb as a ... bob. Cheers, Simon.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.