Hi Rami,
Breaking down your questions based on what's officially documented vs. what needs confirming with your licensing channel:
1 & 2 Where to purchase and SKU name:
Additional storage is purchased as a capacity add-on, in 1 GB increments, through your normal Microsoft licensing channel Enterprise Agreement, CSP, or MCA (Microsoft Customer Agreement) not through a self-serve Microsoft 365 Admin Center marketplace purchase. The Dynamics 365 Licensing Guide confirms this capacity is "available for purchase" in 1 GB increments, pooled at the tenant level, but doesn't name a single universal SKU your licensing channel (CSP partner or Microsoft account team) will have the exact SKU for your agreement type.
3 & 4 Official price and billing frequency:
Important caution here: the Dynamics 365 Licensing Guide does NOT publish an official per-GB dollar rate for Dataverse Database or File capacity overage. Any $/GB figures you see floating around online (including ~$2/GB/month estimates some sources cite) are market-observed, third-party figures not confirmed Microsoft list pricing. You'll need to get an actual quote from your Microsoft account team or CSP partner before budgeting. Billing is generally recurring (monthly/annual per your agreement), not one-time, but confirm the exact cadence with your channel too.
5 CSP/partner vs. direct pricing:
Yes, pricing and billing model can differ depending on your purchase channel (EA vs. CSP vs. MCA) this is another reason a direct quote from your specific channel matters more than any published list price.
6 Does it become available as tenant capacity automatically?
Yes once purchased, the capacity add-on becomes part of your tenant's pooled Dataverse Database/File capacity entitlement (shown in Power Platform admin center > Resources > Capacity), which then allows environment creation to proceed past that 1 GB minimum check.
7 Will you need more capacity later for Production?
Almost certainly yes, and here's why: your tenant's capacity entitlement isn't a fixed number everyone gets it's a baseline plus capacity accrued from your specific license mix (enterprise, activity, attach licenses, etc.). As you onboard more users, attachments, and data volume in Production, consumption will grow. Microsoft sends a 15%-remaining capacity warning banner(both in-app and via email) before you hit the limit, giving you time to react but realistically, 1 GB is just enough to unblock environment creation now; it is not a long-term Production sizing estimate. I'd recommend monitoring Power Platform admin center > Resources > Capacity regularly once Production is live, and budgeting for incremental add-on purchases as usage grows, rather than assuming this 1 GB is a one-time fix.
Bottom line: The mechanism(1 GB increments, via licensing channel, pooled tenant capacity) is well documented. The exact price is not publicly listed by Microsoft that part only your account team/CSP can confirm. Worth reaching out to them now so you have real numbers for your Production capacity planning too.
