I need to build a network of online stores that all have access to the same inventory items (which will contain stock levels, purchase cost to the store, etc.). The individual stores must have access to this centralized inventory and opt to either sell or not sell the inventory items. They should be able to also see the purchase cost of the inventory items, set their own pricing for the inventory items (ability to do this via bulk would be great, like "20% profit for all items in category x"), etc.

Additionally, it is necessary for the individual stores to be able to add their own inventory items to the their stores. Meaning, they are not limited to just selling the items from the centralized inventory.

The inventory would ideally be stored in a single repository so that adds/edits/deletes can be done centrally.

Also, there needs to be a way to categorize the inventory items in a hierarchical manner.

Is there an addon I can use for this? I have never used Expr-esso or Cathrob -- and I'm not sure if those are the only options I should be looking at.

  • This isn't possible out of the box. However, we're working on similar functionality for a client of ours (ability to share store items across many MSM powered sites). If you're interesting, we can sort out a cost sharing agreement: totalserve.net.au/development. The only difference with your requirement over our clients is the ability to set per-site pricing. However they'll be easy enough to implement within our add-on.
    – Michael P
    Dec 2, 2013 at 4:22
  • Which ecommerce addon do you represent? Dec 2, 2013 at 8:58
  • I don't represent any add-on. We've built plugins for both Expresso-Store and CartThrob. However we're slowly porting over our stuff from CartThrob to Expresso-Store. We've internally got a range of add-ons such as CP Order Editing/Adding, and even a Mobile Phone application built (mainly for business owners to create orders when visiting clients) for Expresso-Store.
    – Michael P
    Dec 2, 2013 at 10:34

3 Answers 3


At least with Store, you could do this but it will require some custom development. Out of the box with Store, each MSM site is completely separate and you can't sell items across sites.

However, there are plenty of extension hooks which would let you access the items across sites, and add a site-specific mark-up to the prices.

  • I'm not familiar with Store. Which hooks do you think I'd need to look at? Also, how does Store compare to CartThrob in your opinion? Dec 3, 2013 at 22:15
  • Well given that I'm the developer of Store, I think it's way better than CT ;) In all seriousness though, it's designed to be easier to pick up, and since version 2 is on par with CT in terms of flexibility. Dec 4, 2013 at 8:11
  • Regarding hooks, for example if you wanted to set a custom price based on the current site, the store_order_item_add_end hook would be a good place to do this. Dec 4, 2013 at 8:17

There is not an addon you can use for this. If you use Store or Cartthrob, you will be customizing heavily IMO since your project requirements are so specific.

  • 1
    Hi @Anna_MediaGirl - which parts do you think need customizing? I'm hoping that setting up a hierarchical category is something natively supported. Are you referring more to the individual stores accessing a centralized inventory list? If centralization is not possible, perhaps I just upload a master list to all the individual stores whenever updates are needed? That might be tedious, but that can probably be automated in some fashion. I guess the problem there would be the inventory levels as they'll change whenever a store sells any item. Thoughts? Dec 1, 2013 at 20:19

No doubt there's a hundred ways to do this - but I think you could do it with CartThrob as well - especially since I think they've recently implemented MSM.

"They should be able to also see the purchase cost of the inventory items, set their own pricing for the inventory items (ability to do this via bulk would be great, like "20% profit for all items in category x")"

I wonder if one way to handle this would be to think of the base cost as an MSRP and use discounts, rather than add price modifiers. As discounts are essentially entries stored in a channel, they could be built by/assigned to different stores via status or custom field, and can be applied to whole cart or entire category, etc, etc.

Will take tinkering, but seems possible.

  • Per cartthrob.com/docs/pages/general_information: "MSM Does not enable you to share products or carts between stores however." Does this change your solution? I'm not too sure what you mean by using discounts rather than adding price modifiers (probably because I'm just not familiar with CartThrob). However, the data I get is the cost of the items to the seller -- and then the seller needs to put on top whatever profit they want. Dec 3, 2013 at 22:53
  • I'd talk to Chris. I think MSM support is new - and with your site, I'd want a consult anyway. Price modifiers allow changes per product in CT - and are part of the product entry. But discounts are separate entries and can be utilized more effectively (perhaps) for separate stores. Not your initial request, but potentially another way to achieve the same result. Dec 4, 2013 at 16:38

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