
Big Lemon |

I don't know of any Paizo canon ones, but a fair way to make it less expensive/available at lower levels is by severely limiting the amount of time that can be spent flying.
Sort of like the kirin fighting style feat that gives you a fly speed, but you end your movement while airborn, you fall (making it more like a graceful leap/airwalk than actual flight)

Mark Hoover |

Cheapest one I found:
Wizard with a rhamphorhynchus familiar, 1 scroll of Enlarge Person and one scroll of Ant Haul. Since the wizard starts with Scribe Scroll as a bonus feat these 2 spell scrolls, together, cost 25 GP total.
Cast both spells on the familiar. Now you have a Small sized flying dinosaur with a 10 Str that can carry a little over 150 plounds in it's talons. It's not big or strong enough to ride around (unless you're Small sized and also cast Reduce Person on yourself) but it can pick you up and move you short distances.