This will be a challenging first job.
The paver base material (Alliance or Brock???) may work, but if the existing base has settled and continues to settle, the paver base panels won't help.
Projects typically fail because of poor base depth or compaction. Was edge restraint installed on a properly compacted base which extends six inches past the edge of the pavers? Was a separation/geotextile fabric used? Was polymeric sand properly installed to ensure minimal infiltration of moisture into the compacted base?
The best way to tackle this project would be to remove pavers and base, compact soil, install separation fabric, install proper base material at the necessary depth for your soil and climate conditions (minimum six inches), compact base in lifts necessary for the ability of your compactor, install pavers, replace any missing or damaged pavers, install edge restraint and install polymeric sand.
The paver base panels should not be used as a quick fix.
As neighbor guy commented, this could easily be double the cost of a normal installation.
As DVS commented, you can't price projects with a square foot price.
The use of the base panels would be an interesting material to consider...I for one really want to know if it will work. The problem is, if you are putting your companies name on this project, are you willing to take the risk of not being sure you are really fixing the problem.
If you know this customer well, it could be a good first project.
Try to do the job for time and materials and suggest removal and replacement of base materials as I listed. Use the knowledge gained on this project to help you establish standards you can use on future projects.
If you want to add hardscaping to your business, you probably want to partner with an existing contractor or at least hire an installer who has a good understanding of the time it will take to complete each project. Your supplier should be more than willing to help you estimate material costs, but you will need a better understanding of the hours needed for the labor. Labor will be your biggest expense on a project so make sure you know what you are getting into before you take on a project.