The objectives from a cheap pair of 8 x 30 Kmart binoculars work well.
Surplus Shed usually have some good stuff, Thorlabs/ Edmund are also good but very expensive!!!
Reflection gratings - I always buy from Optometrics (now part of Dynasil) https://www.dynasil.com/catalog/diff...hick-standard/
Project killed by excessive freight charges nearly $150US to ship a 1kg package from Thorlabs, $30EURO the same cost as the item to ship a 100gram package from Europe, so much for amateur science