I was surprised to find that only two Gossamer Albatrosses were built. Is there any way to get or build an aircraft like that today? (I don't mean design your own).
Yes, contact Todd Reichert, PhD, or Cameron Robertson at Aerovelo Inc. They have designed, built, and demonstrated the first human powered vertical aircraft at the University of Toronto, of which they are alumni, and they won the Sikorsky prize of $250,000 for it.
They have aero-velomobiles that can smoke the albatross.
Note: The ability to get airborne in these Ultralights is heavily dependent on the weight and athletic ability of the human operator.
For 20,000 USD You can paraglide on a good day and not need any power except for that of Thermals and wind.
If you really want to have something human powered, then after the chute costs, you can attempt a pedal-based propellor. all chute equipment will run ya about 5,000-10,000 USD, depending on the source, leaving more than half available for constructing your strange propellor.
That said, I highly doubt that any useful thrust will come of it; it'll weigh more than it's worth.
The sad truth about human power is that it's not very good. It's so bad in fact, that it's not worth using in any aviation-related practicality.
Plans for Gossamer Albatross and Daedalus are available if you search for them online. But skills required to build a usable aircraft require some talent and great patience. Depending where you live, materials can be pricey.
Personal experience: I have been working on my own HPA design for >25 years (yes).
I have found that the successful builders are often happy to give you pointers - so find out who they are, and try email them! (I am not going to cause them spam by listing emails & names!)
Building such a plane (on your own?) is an intense labour of love - fraught with great obstacles. It will require great tenacity and an ability to withstand ridicule and disinterest from friends and family.
Easy flier (Daedalus), plans are out there, just google... Speed and maneuverability (Musculair), You may be able to find the plans... Those were the very best (real working examples), so far.
There is yet to be be a practical HPA for sport and recreation. Prizes for one who succeeds!