There are a few places to buy bikes that have some low cost options. So far I’ve only experimented on the NL side, but I hope to add some German stores soon!
Halfords – Sittard (Next to Xenos near the centrum)
(They had a few 300€ touring bikes for guys and some adorable ladies bikes for 230€)
Decathlon – We wrote about this “sports authority” here
Wiebachstraat 75, Kerkrade, NL
Bike Arena Next to Decathlon….
They sell expensive bikes but their used ones are well priced! They also do bike repairs.