AI says ...

AI Overview
Yes, used Croft amplifiers have seen an increase in price
and, in some cases, have roughly doubled in the secondary market over the past 2-3 years.
Following the passing of Glenn Croft, demand has increased for the now-discontinued, limited-supply units, which are increasingly seen as high-end bargains that are holding or gaining in value.
Key Factors for Price Increases:

Availability: Due to the death of Glenn Croft, the brand is no longer producing new units, creating a scarcity that drives up the price of existing used stock.
Market Reputation: Croft amplifiers (specifically the Micro 25 and Series 7) are highly regarded for their musicality and value, often described as "high-end bargains".
Specific Model Trends:
Micro 25 & Series 7: Prices for these models have seen significant upward pressure, with some reports indicating prices have doubled in the UK.
25RS Line Stage: Used, higher-end models like the 25RS still command significant prices (e.g., around £1590).
Increased Demand: Even with the "retro" nature of the design (such as dual volume pots), the brand has gained a cult following that keeps demand high.

While they are still considered good value compared to some competitors, they are no longer the "insane bargains" they were several years ago