Financial Costs Overview

Ultimately, an art website faces mostly similar costs to other websites (and extra bandwidth costs, like other media-heavy websites). Below is a list of expenses to keep in mind, roughly ordered from most expensive to least expensive.

Staff

If you're hiring developers, or any other paid staff - this is going to eclipse any other costs you have, especially for devs. Make sure you know the rates of developers you might want to hire before even considering a project like this if you aren't coding it yourself.

CDN bandwidth

This is likely to be the single biggest tech cost. It might not be the biggest when you start, but as website traffic increases, the amount of data being sent is going to add up very quickly.

This is particularly the case if your media resizing and encoding is not optimal, or if bad caching policies or other oversights cause more bandwidth to be used than should be necessary. The price of your CDN provider, per GB of bandwidth, also plays a very major role here.

Servers

Initially, this cost is going to be higher than your CDN bandwidth, but may later become secondary to it. One server may not seem expensive (e.g. a cheap webserver can be $5-10 a month) but a functioning website is unlikely to use such a small-scale server; you'll likely have 2+ webservers, a load balancer, a cache server, and a database server. Even when starting out you can expect this to be $100 a month or more.

Collaboration tools

Starting out, this can be a fairly high cost just because you will likely have a few of these for different purposes, and the per-month costs are not going to depend on whether you have 1 active website user or a thousand. Naturally it'll scale up a bit over time, if you add more staff members, but this quickly becomes a much smaller cost in comparison to the others as a website business gets larger.

File Storage

While file storage isn't that expensive (and since much of the cost is coming from serving the content to users via your CDN, not storing it), it can be expensive in some cases. This is particularly important if you use lazy resizing algorithms for media, where you might end up with huge numbers of unnecessary resized images in your cloud storage accruing costs that never get used.

Be aware that AWS in particular has an "Intelligent Tiering" option, that automatically monitors object usage patterns and moves inactive objects to cheaper storage tiers (this doesn't affect anything else, it just saves you money really). Useful to know about.

Payment Processor Fees

This varies depending on your payment processor, the geographical distribution of your customers, and other factors (due to the extra fees involved in currency exchange and so forth).

It's also important to note that offering products that have a lower price means you will lose more, in percentage terms, of the total payment in fees. For example, Stripe's fee for international payments is 2.9% of the payment amount, plus a 30c flat fee. As a result, a $1 transaction is going to lose nearly 33% in fees, while a $10 transaction loses around 6%, since the flat fee is a smaller proportion of the payment amount.

Test Environments

Especially when you're still developing a website, or shortly after it begins, the test environments can be a considerable extra cost on top of the live environments, since there's a minimum server "unit" one can provision. Deserted Chateau's test environment currently costs $60-70 per month, as an example.

Security Features (WAF)

Having a Web Application Firewall (WAF) on top of your application improves security, by screening all potential requests as they come in. In itself this isn't expensive to start with, as the fee for having one is usually fairly small as a flat monthly fee, but will have per-request charges (e.g. per million requests). As such it can add up as a site gets bigger, still not to huge levels but significant nonetheless.

Serverless Code & Domain Management

These are both fairly cheap; serverless code is billed for execution time at pretty cheap rates, and domain management is more or less a fixed cost, making it less relevant as a business grows in terms of % of total expenditure.

Example

You can see an example - a plan of Deserted Chateau's expenses - here: https://docs.google.com/spreadsheets/d/131YqanaKd5SsPLaz8zszxltzPczbvFdRaeAzUUhoUYQ/edit#gid=0