IME plastic is fine for typical home use, but check that spares of the perishable rubber bits (seals etc) are readily available, and that it feels stable and sturdy in use. As always, google is your friend for compliments or complaints about particular brands and models.
I got one from Kathmandu a few weeks ago at half price $30. Now they have another sale with even bigger discount, if pumps are included in the sale I strongly recommend the Kathmandu brand. I can't say the same for REPCO
I got a Joe Blow floor pump when i bought my bike ($50 - the pump not the bike ;).
It's plastic and does the job - but it feels flimsy, I can feel the handles bending when using it, and given my weight, it requires a reasonable amount of effort to get the 110 - 120 psi in. The next option was one that cost $100. It had far less plastic - i think it was metal with a wood handle - and it was easier to pump the tyre with. I'm still undecided if it is worth the $50 dollar difference.