Kudos on choosing a gopher, bull or pine snake. They're awesome and underrated animals. However...
There are two catches with feeding a snake parakeets. Even as a snack. First, it is politically incorrect since 'keets are considered cute little affectionate pets, and a lot of small animal owners already freak out over what snakes eat. And unlike many rodents, parakeets are generally raised with the intention of becoming lifetime pets. Yeah, I know rodents are also cute and affectionate but it's partially the unusualness factor. People are accustomed to snakes eating rodents. A snake eating a parakeet will just rub them the wrong way. Heh. It even jars with me, and the only parakeet I've personally known was a little feathery psychopath.
The second catch is that you could have the misfortune of getting a snake who decides he/she likes the taste of parakeet far more than rodents and decides to refuse to eat anything else. A fully grown gopher snake could probably pack down 3 little birds in a sitting. Aside from getting a reputation at every petstore for 30 miles around as a sicko, there's the risk of getting a very expensive snake to maintain.
Your intentions are good, but there are other ways to enrich a snake's life, such as rearranging the snakes cage furniture or adding new things to the cage, such as a cardboard tray of shredded newspaper one day, cardboard wrapping paper tubes the next, or grass clippings. Or you could find a safe, private lawn with no animal burrows to crawl into where you wouldn't scare anyone, and with vigilant supervision let him crawl around a little. Another option is stowing the parakeet money away and saving up for a really nice large cage, with all the fancy features.
I'm sorry to be so negative when you clearly want the best for your snake, but feeding a snake parakeets is a really bad idea.
-----
0.1 chickens (Condor)
0.2 dog mutts (half ownership, only mine when they misbehave, Lucy & Amy)
0.1 Halflinger horse (Crissy)
0.1 Normal phase California Kingsnake (Sophia)
1.1 parents
Still searching for 1.0 WC human