Sticking to budget theme and experimental nature here are some of my experiences.
Standard size for 30cc
Solar 770 and 771 were no where near the specs they posted and were subject to blow back on my 30cc Yak. stay away
Solar 772 on the other hand, while slow, have been fairly good and powerful. I use them in my giant scale Drasik
Hitec 5685MH can be had for under $40 and are good for 30cc, but again on the slow side. They are in Bigfoot.
Hitec 5665MH are the same price point, but not up to 30cc stresses. Most of my throttle servos are these.
HK-15298 is a servo I am interested in. I have one in a warbird rudder that does not fly much. Coreless and HV.
Mini servos
Solar D658s were originally in my 10cc Sabre, but ended up not being very good, they now live in a Ultrastick.
Spektrum A5040s replaced the Solars and I was pretty happy with them.
A5060s were a pretty big failure. They jittered in flight and scared more than one person at the Arkansas FLI.
When it comes to the 60" 3D planes, HS-7245MHs are the best way to go right now. I have tried 5245s and 225s, but they don't handle the speeds and craziness these planes can do with the 1600 watt power systems we now use. I am using the BK helicopter servos (similar to RJX) and I don't notice the difference in speed and they are a bit heavier.
Bottom line is that there is no great "budget" mini servo that I have used.
Micro servos
I have had good luck with Futaba 3114s on my twisted stuff.
If possible use the HS-85 class servos. I have 5065s in some stuff, but the high powered 48" class will get blow back.
Giant Scale standard servos
Not much luck outside of the Solar 772s on anything that can be considered budget. HS-7955, HS-7954, Savox 2270, and Futaba BLS-157/172s are what are in my 50cc and 100cc planes.