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@Keno.hng
I would say that most of what you describe is very normal.
To all the places I have been that do daily trips, operators assume 3 options:
A. Divers have no DC for themselves and rely on the guide's DC, or
B. Divers bring their own DC, or
C. Divers want to use a DC but don't bring one, hence they rent one.
The most common is option A, then B and I've rarely seen C.
Most posters here in ScubaBoard might disagree with this, but most posters here are far from being the average new diver. Here most have at least 2 of the latest/mightiest shearwater DCs (and dive doubles, of course with BPW, multiple deco gases etc etc).
Now what doesn't look normal is the price quoted to the OP to rent a DC as 50$ seems indeed a bit high.
One explanation might be that the intended dives are easy enough (shallow, not too long, long surface interval etc) that the operator doesn't think a DC is needed, hence don't bother to stock enough rental DC. They ask so high price to deter customers from bothering them.
Now back to the OP. You will have this dilema every time you dive. Even if you decide to rent a DC don't expect that anybody will bother to explain you much of how to use it (knowing what your DC is telling you is THE most important thing of using one). Even if they do bother explaining you, you will not remember most during the dive.
The solution? Of course get your own DC! You can get a decent new dive computer for about 300$. Second hand much cheaper. And of course you can get better ones with more budget.
If you see yourself diving for more than few times in your life time - start investing in your own gear. DC should be high up in your list.
Just my 2c as always...