There are a lot of requirements in this question:
1) Price estimate <30$ per module
2) Support CC/CV
3) Digital Control
4) 48V input
5) 90V output
6) 700mA current
7) Module (not IC)
You are probably not going to find something that matches all those requirements, ideally there would be. A good system designer will come up with a list of requirements, but then check to make sure the list of requirements will be possible. If its not possible, then the list needs to be revised with a priority attached to each requirement. I was only able to find designs that met 5 of the requirements, but not all 7. This suggests that the requirement list needs to be revised.
If I drop requirement number 1) and 2) this is found: 36IBX15-50-0G There are less than 5 modules on digikey that fit all of the requirements and none of them are controllable and they are all expensive, this suggests that if you want a module you'll immediate be out of budget if you order from north American suppliers.
This Mean Well LDH-45 series can be had for ~10$ and has PWM dimmable control and analog control, however it does not satisfy requirement 4) because it has a 32V max input, in this case, it would probably be cheaper to switch to a module like this and get a new power supply. It also doesn't really do CC/CV, but does have PWM control which makes it digitally controllable so requirment 2) is also nixed.
If I drop requirement 7) and 5) I get the LT3956. With engineering usually time and cost are traded off. There are other IC's that would If you have time, then use an option like this and do a PCB design. PCB web takes most of the confusion of PCB design. (they already have most of digikey's stock in the PCB web library which means you don't have to keep track of parts or draw footprints 98% of the time, it generates a bom and you can automatically order the PCB) If cost is an issue, then this would be the way to go. However there are no IC's searchable on digikey that will boost to more than 80V. Yes it's more complex, but if you have some smarts usually implementing a design from a good datasheet schematic will be fairly easy. If you go this route, make one or two (you can even have them assembled) to make sure it works and then make 10.
There are too many requirements for this project, you could change a few of them. Pairing down the 48V Input requirement would give you more flexibility to choose modules that might have a digital option. If you split your 90V requirement and split your LED string in half, then you could also open more modules up as good candidates. If your going for price, then roll your own PCB, this also give you more flexibility.