Reddit mentions of Reneeze Womens Beauty-03 Sneaker Petty Stacked Heel Side Zipper Ankle Booties,Grey,6.5

Your link is taking me to all dresses rather than a specific dress.
However, I can at least make a general recommendation I don't know how your gf feels about color combos, but some people are really particular about wearing black and brown with certain things, and if that's the case with her a really great compromise can be grey because they will go with both black and brown.

her overall style will determine what boots work better for her. How high of a heel would she be comfortable in? and what would you consider not too expensive? I have these in lead and really love them, but they are on the pricier side. This could be another less expensive option. I also think these are really cute if laces are more her style.