Web scraping for inventory syncing - Shopify site

As an initial pilot, we would like to sync our inventory with our supplier, Muscle Nation. We need to sync most (90%+) of items in this site
https://musclenation.org/

In the example page below, you will note that a few sizes are 'greyed out'. We want to update our product records for each item to reflect the sizes as out of stock (inventory = zero). For the sizes in stock, we can return a dummy quantity of inventory (say 10). This data needs to be collected across all products on the supplier site and synced with Shopify.
https://musclenation.org/collections/bike-shorts/products/bike-shorts-navy

We would like to sync inventory perhaps daily but this could be more/ less frequently based on the degree of difference we find between sequential scraping sessions.

We are not looking at "scraping as a service" for our solution, due to the frequency that this needs to be run. Rather our preference is to have something built that we can maintain and configure the frequency of running ourselves and reconfigure to use with our other suppliers. We are a small eCommerce business and therefore do not want to have significant ongoing costs for this work.

Please let me know if you require further information to be able to scope the job. We have other pain-points relating to product data management and automation of our overall order processing flow that we can also look at down the line, but solving inventory is our highest priority for now.

The expert must provide a high confidence estimate of the effort required. Ideally you have done this exact work or something very similar previously - this project is not a learning exercise. Please provide details on your previous experience in your response. Priority will be given to experts who can demonstrate that they understand the problem and challenges and can show where they have done this before.

Please do the necessary preparation before quoting as there will be minimal scope to vary from your initial quote, once accepted and work commenced. Please also ensure that your technical solution will work with this supplier website - confirm first that your scraping approach will not be blocked by the supplier. We have no idea what (if any) defenses might be in place to protect against scraping.