The phenomenon of transpiration, which combines evaporation and capillarity, could be used to autonomously and spontaneously drive flows in pump-less microfluidics. While previous studies have shown diverse experimental applications, no comprehensive theoretical analysis has been done on these processes. Here we perform parametric studies on the system, with emphasis on studying the feasibility of a low-cost version of transpiration-based microfluidics, which could be fabricated using inexpensive and readily available materials (e.g. cotton threads and tissue papers). Our analysis is particularly focused on the geometric variation of the system, including the ratio between cross sectional area of capilarrity parts and evaporation parts, as well as the wind velocity at the interface between the evaporator and its surrounding ambience. Our results serve as general design guides for low-cost transpiration-based microfluidics.