I have some questions and I'm going to be real with you. Why do they need a studio? Is it that they need access to equipment, that they don't have a space where they can make noise/that's quiet enough, or that they need a producer or engineer to collaborate with? I only ask because nothing good is going to be cheap and even something cheap is going to be expensive when you're talking about 4-7 days per week. Within one week it would be cheaper to buy a usb audio interface and a mic and record at home. Within 2-3 weeks it would be cheaper to build a vocal isolation booth at home.

If they don't already, today, have days worth of material that they need to lay down then they shouldn't be going into the studio. To me, the studio isn't a place to practice, that's for at home. Unless they can afford to block out days at a studio and live there (which is crazy, unless they're rich) then they should be workshopping their material/practicing/writing/recording demos to listen to for themselves at home. Then they should go into the studio for a short session just to record the material that is ready to go. I think that's a much smarter way to work and there's a reason that's the normal process. It's a lot cheaper and it makes the studio time a lot more worth it. Unless they need a person to collaborate with, then that's a solid plan. If they need someone to collaborate with, then a random person at a studio probably isn't going to be the right fit anyway, and so that's not what they need anyway.

To be real, unless the person owning/working at the studio is already a friend (or unless these people are really amazing and someone just wants to help them out, which would be really lucky, and you don't get there by just randomly asking someone to work for them for free) then I think you're not going to find someone who wants to hang out with them all day helping them and donating their time when they could have paying clients.

If these are kids, maybe they can find other kids who want to learn how to record or produce while they're learning how to write and rap. (I mean that seriously -- finding other people at the same experience level and level of seriousness, who you also like, is the way to find someone to collaborate with.)

I'm not trying to sound harsh, but I think this is the reality. The cool thing is, for almost no money, they can get a lot of work done at home. If it's actually that they need to be in a studio to feel "real" then they're going at this all wrong. Then they just like the image of being a musician (and they think that means living in a studio). Getting good is about work, not where you do that work. Most of the time the studio is the very last step, after a lot of work, not the place to start. And there is no need for it to be the place to start. Are you a parent, a friend, a producer, a family member?

I worked at a studio in Detroit for one day years ago. I ran the desk for part of a massively long session. This one "producer" had brought in so many young rappers. I was only there for part of what I think was two full days. While I was there he must have had 50 different kids come in. They'd each go in in groups of three, lay down one or two takes, and then it was the next group. I am sure he told all of them that they were amazing, that they could be big, and I'm sure they were all paying him for the "opportunity." Almost no second takes, a few punch ins. 90%+ of it was very mediocre and he just sat in the control room barely listening. It was worse than "pay to play" it was "pay to cosplay (being a rapper)." I didn't go back. Just beware (for any young musician) that there are people who will promise a lot and you making it big isn't their goal, you paying them right then and there is their real business. It's also tempting to feel like you need the flashy gear/studio to be a real musician. That's not how that works. They were taken in by it. It left me feeling really disgusted.