Despite what people keep on telling students, your essay doesn’t have to be about How I Overcame Adversity. In fact, using that particular topic risks cliche.
The point of your essay is to show something about yourself which the AOs will not read in the rest of your application, specifically, something which will cause them to think “that person will be a great addition to our student body”. Wring about something that you really enjoy doing is the sort of topic which is great for that purpose.
In short, thrift shopping is an excellent topic for an essay. Just remember the first three rules for writing:
A. Show, don’t tell,
B. Show, don’t tell, and
C. Start by writing in a foreign language…
Joking, C is also Show, don’t tell.