Outstanding varnish jobs can applied by brush. All that is needed is a good badger hair brush (look in marine catalogs), good varnish (try Z-Spar's Captain's varnish) and practice. No compressors, complicated masking, spray guns, etc. Brushed varnish will look more traditional and in keeping with a wood.

Key points are do not overly thin the varnish and don't fuss with it. Thin only as is needed to get the brush to flow, not drag (usually not more than 10%). When you brush, don't fuss with it. As my mentor taught me years ago: "Dont play with it, put it on the boat!") From the second the varnish hits the work, it starts to setup. If you keep patting it and fussing with it, it will not level properly. Once you start, keep the wet edge going. If your arm is tired when you get done, you did it right.

Spray equipment is almost essential for a water-wet urethane paint job, but varnish can be done very nicely with brush if you work at it. The problems you will encounter will be no less difficult and a lot less expensive to overcome than you will experience with spraying.