@IslandDan2020 welcome to Scubaboard. I am from Crete/Greece and I'd guess that we get similar temperatures over the year i.e:
Summer around 25ish (with max at the surface surface ~28oC)
Winter around 18ish (with min at the bottom at 16oC)
Spring and Autumn in between.
Most of the time I am using a 5mm two pieces (long john) Cressi Medas wetsuit I bought from planetmultistore.com for around 136euros last year. It seems it is still available for that price:
PLANETMULTISTORE.COM - Cressi Medas 5mm Man | S | Diving - Wetsuits - Dive Wetsuits | Planet Multi Store and I am very happy with it (for the price).
In summer (temperatures 25+oC or so) I use a Seac Sub Relax 2.2mm full body suit. It claims to be 2.2mm but it measures (with calipers) to around 1mm and in water it is actually negatively buoyant. Hence it is more like a rush guard / cloth material instead of neoprene, but it is perfect for summers and for my trips to the tropics (covid permitting). It sells for around 65euros.
When things get cold (reaching 20ish degrees or less), I add a 3mm vest inside my long john and if needed a pair of thin gloves. With those I get cold but managed to dive throughout last winter.
Since last January though I have managed to loose about 1/4 of my weight (I was about 115kg, now I am 90kg or so). Now I am feeling cold much easier even top side hence I doubt I can dive winter temperatures with the long john/west/gloves combination any more. Last dives I did before the lockdown were on the 2nd of November
(it feels much longer) with 23oC and I was just ok with just my long john. No more diving for us here until further notice hence I don't know how I would cope this year.
As you can tell I am on the low budget side. Of course there are better (and more expensive) options out there but most of them are out of my budget.
For me next step is drysuit. I wouldn't fancy to be wearing more neoprene than a 5mm long john + 3mm vest
All the best...