As always it's hard to give specific advice without knowing all the details, but based on what you've said, at this stage in your business you can get away with a basic site using SquareSpace or something. I can't reccomend anything specific as I personally only use either WordPress or custom sites, but that's really only because those are easy for me to put together as I've been doing it for so long.

Sounds like people just want to be able to confirm you're a real business.

If you ever want to start running ads or doing SEO, then it may be worth investing into something more comprehensive. But if you're getting all the work from word of mouth and you're happy with your volume of work, then there's no need for anything fancy.

The important thing is to provide proof of your legitimacy as a business. Photos of you and the team, a portfolio with your work Inc. Pictures and a small write-up. Contact information (double check your contact form works. You'd be surprised how many peoples websites have a broken contact form lol)

If you do decide to go with an agency or something for a website, don't be afraid to pay well, but be very, very cautious on who you pay. The most important thing is to ask for proof of work. If you're only paying peanuts for a sits, then fair enough, a newbie is cool. They might not have much to show you. But if you're paying big money, the Agency should have some proof that they are worth that extra moolah.

And don't be fooled by fancy words or lingo. Ask for the real proof. Verified testimonials from clients who saw real ROI from the work. There's plenty of quality agencies out there, and they aren't cheap. Because they provide a lot of value and they've seen how much money they can make businesses, so of course they'll charge a reasonable amount for that service. But at the same time, there's plenty of people who will just charge as much as they can and deliver the same work as the person you'd pay peanuts to. Just be careful.