ive got the bare cheek to go into b and q...i pick up a level and walk to the timber section...split open the kiln dried batons packs of 8...and check them for straightness...i take the straight ones and leave the bent ones and leave the level...
I use my local timber merchant and get planed lengths with no knots in, they tend to be pretty good. Normally get a 5m cut it to 3 and 2m and that does me one or two jobs. Much cheaper than BnQ