There is a profitable club close to where I live that might be 3000 square feet total at the most and it's probably close to 2000 square feet. The club itself is less than 1000 square feet, there are a small number of private rooms that are upstairs above the club.
If you want to open a club that doesn't serve alcohol you can do it for less than $100,000 in Pennsylvania. Strip clubs are cash cows even without selling alcohol. Hire an attorney to find a town where there aren't any rules about needing a business license or approval from the town to open a business. Find a vacant building in the town that is in good physical shape, lease it, and hire a crew to clean it out. An empty storefront in a strip mall is good enough.
Do something that looks decent to cover up any windows so that no one can see in. Painting the name of the club and a couple of girls in bikinis on the inside of the windows and then paint over that with black paint and you'll have something that looks good and that can't be seen through. Then put walls in front of the windows so that no one can break them and see in.
The expensive part will be hiring a carpenter to build the stage. Don't skimp on safety or on a smooth surface for the customers to rest their arms. You don't want any lawsuits.
A good enough sound system will cost less than $2,000. You only need 4 speakers, one in each corner, and it only has to be loud enough that customers can't eavesdrop on other customers negotiating with the dancers. You will need to install dim lighting with a few "spotlights" focused on the stage to light the dancers when they're on the stage. Flood lights with a dimmer will work just fine.
Chairs for the customers to sit in and tables are inexpensive. You're not furnishing a 5 star restaurant and the lighting is dim so no one will notice that they're cheap. The same with the floor, concrete will work except in the lap dance area.
Security cameras aren't that expensive. You'll probably need a dozen of them and a computer to monitor them. $10,000 will let you cover the entire club.
Buy cubical walls for the lap dance room and the "private rooms". Make the "rooms" big enough for love seats and put the love seats where you can't see them from the door without poking your head in. Buy love seats for the lap dance area too and put them all in one "room" made of cubical walls with a bouncer to monitor things.
You'll need a standing desk at the front and in the lap dance area with cash boxes, an ATM, and have the carpenter build a bar and give away bottom shelf alcohol. A $20 cover will easily pay for the amount of alcohol most guys will drink. Buy the love seats and tables for the private rooms and lap dance room from a furniture store that's going out of business. Who cares what color they are, it's going to be too dark to see anyway.
There you go, less than $100,000 up front for a dive strip club that will bring in an easy $15k a month in profits in the slow season. And don't computerize anything. Cash only with cameras watching the cash boxes so that nothing can be proven and the IRS won't have any documentation other than the paper sheet that you fill out by hand every night on how much money came in.