Lidl, Aldi and similar low cost supermarkets have the cheapest raspberry canes and they have always worked for me. If you want an unusual variety then you may need to pay more, but for your first venture into growing soft fruit all you need to know is whether they are summer-fruiting or autumn fruiting.
The two main classes of raspberry are pruned in completely different ways. Autumn fruiting canes are cut down to the ground in late winter. Summer fruiting raspberries will fruit on the previous year’s canes, like blackcurrants, so you cut back old canes after fruiting has finished.
You only ever need to buy a few raspberry canes because they will spread like weeds. To propagate raspberries all you do is to stick 12in lengths of cane into the ground. Use your prunings. You do not need rooting powder, just stick them in.