We recently picked up 2010 eastern desist and wanted to fix it up for our 12yo son. We Upgraded to hoder handle bars, odyssey stem, odi grips, new upgraded seat and odyssey evo 2 brakes. Needless to say when all said and done we spend about what an entry level bike would be so now I'm torn. What in the end is a better bike the one we put together or a stock fitbike co long 1 which I can get on sale for about $320.00. He's just getting into bmx bikes because that's what all his friends have so not sure he'll appreciate the upgrades parts but is a new bike better?

Any bike is better then no bike! We all had used beater BMX bikes BITD, and then upgraded later. What's most important is that it fits him, and isn't too heavy for him.

In a year or two he'll probably outgrow a new starter bike anyways.

2 styles of BMX .. Racing Motos, an Olympic event in London & Rio, and stunt riding, Red Bull X games stuff.

what does the kid like to do?

Was your son involved in all the upgrading? My experience is that kids generally go for new-and-shiny over old-and-worn, but that can change when the kid is the one bolting together the parts.

Have you asked your son which he prefers? Maybe just ask him.

cbrstar mentioned fit. Here is a link to a sizing chart with some general guidance:

SIZING FOR BMX BIKES - Find the right size Eastern Bike

And USA BMX also has a chart:

https://www.usabmx.com/tracks/1709/pages/492