[justforthispost]

You'd do well in exploring alternatives that don't involve equity.

Have the other clients accepted your new rate? Do you expect to easily get additional clients at the new rate? If so, then you could work on a compromise with client X (the one who "can't afford" your new rate), e.g.

(i) lowering total number of hours per month you work with them, such that the total bill works out about the same as before. Proactively suggest scope cuts. If you know more or less how much revenue (or how much savings) they get due to the projects you do, you should also have a good idea of what features lead to more gains for them.

(ii) give them a discount, or even better, give them a number of "bonus" hours for free, as long as they order over x hours in an n-month period. Think of it as giving them the option of locking in a lower price in exchange for ordering in bulk. They get a lower price and you decrease the risk you won't have enough income in that period.

[eggsalad]

Instead of equity I've also been thinking of a commission on each product sold, once the product gets to market. Hopefully it will be ready for sale in 6-9 months, but there does appear to be significant demand for the product, so that might be a good alternative to equity.