Sugden Audio team recommends particularly the A21a if you’re in search for the used Sugden amplifier, that both keep the value and still provide great sonic impact… 

“As a result of Sugden producing amplifiers for fifty years, there are a lot of preloved items that can be found on the second hand market. This is a way for anybody on a budget to get a great sounding amplifier at a reasonable price. Quite often we get asked which second hand Sugden they should buy and there is one item that is top of the list, the A21a. These were produced from 1990 until 2006 so there are a few thousand spread around the world.”
They are reliable and only require basic servicing to keep them up and running. The A21a also holds its value incredibly well and you can usually sell them for the same price they were bought for. In a way it’s like owning a Sugden amplifier for free.