I'm frustrated with my single-speed project

I was all set and excited for the conversion of my Marin Alpine Trail 29er into a single-speed. I have the budget; and, I already practiced and trained for the single-speed ride.

I went to the bike shop this morning to have the conversion done. But, the mechanic told me that the front crank of my 29er bike could not be dismantled because the plates are riveted and not screwed.

So, I asked him what my options are:

1. Go on with conversion but my front crank would still have three plates although the biggest and the smallest plates are useless. But, this is not good to look at. And, it would defeat my purpose of shaving off some weight from my bike.
2. Get a new crank. The available crank at the shop is very expensive.
   

My other option is to buy another 29er with single speed. But, I need to save first for this option.

Meantime, I'm postponing my single-speed project and think all over again.