Well i dunno,50 quid for a very good sounding amp but then there are these days a lot of great sounding 5-15 watt amps...but this is the cheapest i've ever seen(heard). If i was in the UK i'd probably buy one tomorrow.
If you know what you're doing then most anything is going to sound good. Of course it's all a sum of the parts (person, technique, mic, amp, environment...). The biggest confidence boost for me is just being heard and being able to hear myself. What that takes varies from situation to situation.
I think I should do small amp demos and make some money on the side. Would you buy this amp?
I've had a few low watt amps, from Pignose 7-100- a few watts, to Fender Princeton Trem- about 10 watts-, Fender Vibro Champ- 5 watts- and for some years I've favored a Silvertone 1482- 12 watts. I'm in a duo and we have matching 1482's, which work well for us in small to medium rooms. I've had big amps as well but this is about lower watt models. Mostly a 5-15 watt amp is a good candidate for practice, duo or solo work, or a particularly low volume combo band. While I've seen a Fender Blues Junior do ok in front of a loud band it was an exception and also because the player had his amp up front on stage. I doubt the back of the room could hear him even so.
What are you looking for? Practice? Duo? Bigger band? One big challenge for a lot of harp players is, they may not be heard in a band where drums are loud and bass and guitars etc., all are sporting 50-100 watt amps. Usually a harp mic will feed back at much lower volume without a harp-specific built amp. Small watt amps can be great for small room/studio stuff but will totally distort out past reason in a big room or outdoors. You have to know what you're going for when amp shopping.