How much money do I need to get the necessary amount of Crowd Search credits?

City search per minute equals 30 credits.

The credit value differs from $0.018 to $0.01 per credit depending on the volume you purchase. Visit for more details.

If you choose the $0.018/credit package, the cost for doing two 3-minute city search would be $3.24 and in 30 days, $97.2

For your 4 major cities, you will use 360 credits for one 3-minute city search. 
Two searches per day will use 720 credits. For 30 days, it will be 21,600 credits which will cost $388.8

You do not need that high of a budget for crowd search.

Although city search is the best option, you can try mixing it up with all three, that'll do just fine.

There is country search per minute which uses 5 credits and there's also state search per minute for 15 credits.

Crowd Search strategies:

For a website that's not in top 10, using crowd search is not advised.

If the price is not affordable, then don't do it.

Instead, we recommend getting organic backlinks.
Go to forums and niche blogs related to your site and leave comments.
Contact blog owners and write guest posts for their blogs in exchange for links.

Build out more city pages 

There are lot more to do with your TIME instead of spending money.

Crowd search is not the cheapest option, 
it is a springboard? YES, but not a MANDATORY step.

You have to choose wisely according to your business model and budget.