Need some advice for new networking design

Hello networkers,

i am IT/Broadcast engineer at my organization and except that someone offer me a side job to run and design network for small organization. i have good background of networking and working in this field for almost 3 years except that currently i finished both OCG CCNA books and did Chris Bryant , Neil Anderson and David Bombal course and did many of labs. but i have a problem with choosing best products for example now we have to find a firewall for organization with +20 Users can someone help me please. not expensive one neither cheapest one.

Thanks in advance , Doski