Having been asked my advice on starting a company (usually of one), my advice tends to start with: buy the coffee.
Since running my own business I'll always try to buy the coffee when meeting a client or customer. Meaning more that I'll try to pick up the bill after our meeting.
Partly because I (might) want their business and it's my way of saying thank you for your time, I know that it's valuable.
It also avoids any awkward toing and froing on who should pay or worse still splitting the bill.
In the scheme of things a £10 bill barely a dent on the money that will be invoiced for, even if the project is in the hundreds of pounds.
Caveat: if, and only if, you have the cashflow do I think you should follow any advice you find in this post. If you're struggling or tight on cashflow, then do what you need to do to ❤️
In addition, I have a rule that if someone recommends me to a client and I get that business, I'll say thank you (after the client has paid and usually at the end of the year, like Christmas) by sending that person (who recommended me) a crate of wine (or some such appropriate gift).
I try to be generous (or what I think might be generous), so it can be anything from £100-£200 but again, it's barely a dent in the money my business was able to invoice for. It also (hopefully) says that I value their recommendation. Because I really do.
Paying for misc "stuff"
Which brings me to: paying for software or services.
I really like paying individuals for their work. Individuals who have worked on a self contained product and sold it on (something like) gumroad, or some software that I can use and rely on, or perhaps have written some book or resource.
The books/videos/resources products are an easy sell on me. If the individual responsible for the work is recommended to me or I'm already familiar with their work, I know that their content is going to be useful and of high quality.
It also means that now I don't need to search the internet for how to solve that particular thing, I can use this newly bought resource guide and I know it's a reputable source of information (which is the hard part of scouring the web).
Then there is the actual cost. Generally (and for me), anything up to around £200 is reasonable enough that it's worth paying for. That's because the investment will be returned in my own work later down the line. If I have the option to pay different rates (like gumroad allows you to), I'll choose to pay more. I pay more because I can and because I think the creator will like to have more.
These are all business purchases. They are all purchases that make my business better in some way and "better" typically leads to my business earning money, which lets me live. Which I value the most.