Best way to build shelves?

I will be growing a lot more plants from seed this year.  I started this last year, using metal shelving and fluorescent lights and some space in my basement.  I grew several hundred plants, some for sale and some for my own garden at the farm.

This year I'm increasing.  A lot.  As in, my seed orders have begun arriving and my poor husband just walks by my office shaking his head.

So.... I'll be needing more space.  Lots of it.  I don't want to spend the $30 per metal shelving unit that I spent last year on my 2 racks.  Although these racks were convenient, because they had rails that I could hang the fluorescent light fixtures from.

I'm looking for ideas!  So far I'm thinking of wood planks & cinder blocks to set up for temporary shelves.  This would be great because when the plants are sold or planted, I can take them down & store until next year.  Anyone have any other low-cost ideas?

I'll also be needing extra space.  My husband came up with a plan that involves clearing out my office (which is in the sunroom of our house) and filling it with shelves.  This is great, because the walls are full of windows on 3 sides and if I take down the sheer curtains I may get enough natural light that fluorescent light fixtures wouldn't be needed.

Not needing to buy more grow lights is definitely a bonus, because I'm still reeling from the hundreds of dollars spent on this year's seed order...yikes.

Clearing out my office gives me the shudders, though, because I have no idea where my sewing table & desk with computer would go.  One day at a time, I guess.

Should I be pleading for help yet?  After all, I still don't have a farmer's market to sell at this year...