I'll second Fox Microns.
I have 3 x MX+ alarms that have never given me a moments problem since the day I bought them.
I have no need for a receiver as I bring my rods in at night and am always "on" them at other times.
You can pick them up new for under £35.00 each if you shop around, and I personally think they are great value for money.
Separate tone and volume controls, and a very simple "toggle" on/off switch which I like.
The blue LED light is very bright (repeat VERY!!), you can see it instantly. In the dark it will easily light up the surrounding trees so you can even run them on "silent mode"
The other bonus with them is that they run on simple AAA batteries, which are available anywhere.
My Daughters previous alarms (she now has the same Microns as me) required a tiny little battery which wasn't available everywhere, and it was a right pain in the butt if you needed replacements in an emergency.
I appreciate that Delks and the like have a following, but I can think of a lot more things I want to spend my hard earned on, and a hundred ££££'s or more saved on alarms would allow me to buy "better" reels, landing net or luggage for instance.