If your sole need for an applicator is to spray weeds on your allotment path, I suggest you save the capital cost and buy the cheapest watercan with a "weedol" bar. Paint a "skull & crossbones " on it and only use it for the job. Depending on whether you aspire to lawn perfect paths or prefer the scorched earth look, buy a dilutable product accordingly. Not only will you save the investment but you also reduced the chance of spray drift killing your plants, or those of your neighbour. Personally I limit to rotary mowing and let the little speedwell types flower. Many of my erstwhile allotment colleagues would have been content to see the elephants grazing on their wildernesses!