Tight budget, understand that. Give some more info as to what you are trying to accomplish. ie, what and where are you trimming? Diameters, volume, how often?
Then better recommendations can be made.
One advantage of manual saws/pruners is that you don't have to feed them if not using them. ie, they don't deteriorate like a saw will. It is also something that can be kept for a lifetime and used as necessary even if it is only once a year or two. So think about that.
If you have the ability to generate revenue, then you really want to invest in something that will allow you to generate more income. So speed is important. a $500 tool can pay for itself in a couple days if you have the work for it.
I purchased a Marvin pole pruner/saw combo AFTER I already had the Stihl 101. They are two different tools and each have their place. The segmented poles work well to set pull lines and can reach farther up than the Stihl. A manual pole saw can do everything the Stihl can but not vs vs. I wouldn't want to have just one though and use them both.
Our tree service is very small so I can't invest in too many specialized tools but most of the tree service stuff also does duty for property maintenance in general.