In uk.rec.gardening Adam Aglionby wrote:
Aldi had a limited selection last week and Lidl have currently wide
range flower and veg seed at 29p pack, average1.2g, had good luck with
Lidl`s tubs of random seeds in past couple of years, compares well
with average ?1.99 from a big name seed packet.

Even cheaper (well, kind of, ignoring the amount we spent on other
items and the travel costs!!), we went to a Potato Day yesterday with
a seed swap, and exchanged a load of my leftover spare tomato seeds
for, well, different tomato seeds mostly.