Clothes are expensive in Germany, but there are a few places to find some affordable items.
H&M
Is now a recognizable world brand and has affordable stylish clothing. They have a shop in Bad Godesburg center (Fronhofer Galeria, Am Fronhof 953177 Bonn) and several in Bonn.
C&A
Affordable clothing for the whole family. Shops in the centers of Bad Godesburg (Am Fronhof 9, 53177 Bad Godesberg) and Bonn (Bottler Platz 3-5, 53111 Bonn).
Zara
Fashionable clothing and home decor from Spain at a reasonable price. In Bonn center there is a clothing shop and the home good (mainly linens) at a shop further down the street (AM MARKT, 13-21)
Deichmann
The most affordable shoes in the area. There are shops in the centers of Bad Godesburg (Am Fronhof 9) and Bonn (Sternstrasse 18-20).
TK Maxx
The same as TJ Max in the US. (Munsterplatz 15-17, 53111 Bonn)
Lil'Champs
Lil'Champs is an actual kid / children's dress online store with cheap price.