Phase 3 and Phase 4 are combined regarding the payment structure, since they follow the same principle.
If you are the one ordering the products we decided on (or parts of it), I will only invoice my hourly rate to compensate for my time spent selecting them. However, if I oversee ordering, meeting the delivery team on site, surveilling the installation and potentially having to deal with damages that occurred to the product or your home, then I will waive the hourly fee for the aforementioned, but utilize a “cost plus” with a 20% overhead charge.
There is also a possibility for a “mix-use” model: you as the homeowner feel comfortable purchasing furniture and appliances, as well as décor items on your own, but do not feel equipped to successfully oversee the tilework, countertop installation or interacting with subcontractors.
In that case, we would default to a “mix-use” model where I will bill my hourly rate for selecting products and a cost-plus for the work I oversee, which is no problem at all if it was agreed upon and understood prior to the start of Phase 3.
As you can see, until we have had a chance to talk about your project, vision and desired involvement, it is impossible for me to give you a “ball-park-price”. However, I can assure you that before we start the actual work, both parties will have signed a step-by step plan of the key milestones of the project, alongside the required deposits before moving on to the next step. There will be no shocking surprises at the end.