I’ve been looking through info for some indication of single supplement possible costs
You’ve put this under “Tourist Scams”.
What is your question?
Costs for anything in particular?
The cost for a single supplement depends on the company and on the tour. For instance, the costs of a Single Supplement on Rick Steves tours are listed on the Overview page for each tour. Prices depend on the tour - Best of Paris is $775. Paris and the Heart of France is $925.
Looking at the Road Scholar program page, their version of the Best of Paris tour has a Single Supplement of $670.
Some tours offer discounts occasionally of single supplement fees. For example, I signed up for a Gate 1 tour of Romania when they had a sale waiving single supplements. Some tour companies never have single singlement fees on all or some of their tours, such as Seymour Tours (never) or Overseas Adventure Travel (OAT) (on some tours).
So it does pay to shop around.
Gate 1 has had two sales per year where they waive the single supplement fees. These are worth looking out for.
A single supplement really isn't a scam. Was it a mistake to put it here?