ISRC codes used to be free. But now you have to pay for them.
If you really want them, go here and get your first owner codes:
ISRC - International Standard Recording Code (they are now $75 for the first 100,000). Then you can make your own for life.
As far as UPC codes, you can get those just about anywhere for around $35.
CD Baby is probably the best bet for them.
Digital Music UPC Barcodes - How to Sell Music Online
But really, if you think you're going to make your money back on your ISRC registration codes, you might want to do the math.
Royalty rates (via reported plays) are so low now that for the $100 you're talking about just to get the codes, you would need to get about 100,000 airplays to break even - not likely.
So go for the direct sale. Screw the big business guys. They don't give a !@#$% about you anyway. They're only looking to make their bottom line bigger.
The people who are interested in buying your music can download the files directly from you and you can keep 100% of the sale.
Also, if you make your music ONLY available on your site, then it makes it 'special' and you can control the supply. (not to mention, you also have the ability to make 'upgrades' to the mixes later and re-sell (or give away) the improvements to your customers.
Put it on iTunes and everyone assumes it SHOULD be priced at .99 cents... STUPID! Not only that, but you're competing with EVERYBODY ELSE on those huge sales portals. Not a good situation at all.
If it's only available on your site, then you can charge more for it because of supply and demand. Also, you are free to make 'collections' and 'compilations' on down the road simply by 're-packaging' the downloads into new products. (i.e have an entry level product, a mid-level product, and a high-end product all using the same material but packaged uniquely).
That's my suggestion anyway and what I've been doing for the last 4 years or so.
I still have my stuff listed on iTunes, Amazon, and CD Baby, but there's not enough sales to spit at from those sources.
But I still make a decent income from direct downloads.
So my two cents is that UPC and ISRC are icing on the cake and I wouldn't worry about them too much. Sell via direct downloads and screw making physical products.
Who wants to spend the time shipping that crap anyway? And it's an oil based product that puts this county further into debt to big energy companies.
Obviously, I'm opinionated. Sorry for the rant.
Good luck!
PS
(It's a good idea to give away a good portion of your products - encourage your customers to make YouTube 'fan' videos)