Hi baza
When you first asked the question last week, I had in mind (prob incorrectly) that you were asking about a two pole tester for checking circuits are dead before working on them. The martindale I suggested is really mainly for that, and for very basic continuity. In addition I use a multimeter for fault finding etc.
If you want a safety tester that will also double up to do measurements (ie instead of having a multimeter as well), then you need something more advanced than the Martindale.
Personally I think the advice to go for the Fluke T150 is good, but I appreciate it's expensive.
If you check 'sold' prices on eBay, you can find a few that sold for £60 to £80 fairly recently. There is a risk in buying such (I wouldn't recommend the Chinese source) but at that sort of price you could probably sell it on if there turned out to be a problem! You might be able to afford to get it calibrated too!
I've bought literally thousands of items from eBay, and very rarely had a problem, even with electronics (eg TV circuit boards, appliance spares) although these days eBay prices can be higher than online retail.
Ebay bargain Computers, tablets, phones I keep away from!