I would start with an old singer or similar. You can always
upgrade, if necessary.
You can get one in good working condition for about $50.
Mine easily sews through a double layer of Sunbrella and
two layers of sail cloth on a furling jib's edge. More layers
towards the eye were difficult.
Get a model with zigzag and reverse, ~1940s or 50s. Older
ones only do straight stitches, newer ones are flimsy.
Mod. 99, 66, 201, pretty much every old black and gold
machine will do.