I say go ahead and fork out for a banjo 2" y-strainer, with 50 or 80 mesh screen, because you'll be saving so much money already going DIY, but you can get away with a 3/4" or 1" one if your feeling lucky. I don't reccomend them, because they can clog up way faster. Some of the parts needed for the return manifold will change depending on what size y-strainer you pick, but just a few basic fittings anyway. At least find one online that is 1 inch, with male threads if you can. I'll get to that more...
You'll need a 1" PVC ball valve that is NPT threaded, not the slip/glue kind. Better to be able to unscrew the whole 1 inch return line section, than glue it all up. Same with a few other parts.
As for the rest of the fittings, as you can see on the pic, for the bigger manifold sections you'll need:
5 x 2" PVC 90 degree elbows. Some could be s"street" elbows that are even more compact, but cost more, just use normal, for better flow)
1 x 2" PVC Tee
1x 2x1" PVC reducing Tee (slip or NPT for the 1 inch outlet, whatever you can find) (edit, you can also get another regular 2" tee like the one above, and glue in a 2" to 1" reducer bushing fitting, which might be even cheaper than the fancy reducer tee)
For the 1 inch return line section, like I said it kind of depends on what filter you get, but if you go with a 1 inch drip system y-filter, you just need whatever fittings it takes, starting from a Male PVC adapter, or pipe nipple, that screws or glues into the 2" reducer tee listed above. Then from there you just use a regular male 1" adapters to screw into the ball balve, and another one coming out of it. Same with the filter, so 2 more, possibly females. Then, you finally end right before the pump with a "1 in. x 3/4 in. PVC Barb x MPT Insert Male Adapter"
...which has a hose barb, to match the input fitting on the pump. Just connect them together with a short piece of 3/4 black tubing, which is all you need for that small section.
You'll also need a few more 3/4 barbed elbow fittings, to complete the final section of the tubing for the loop back to the res. N/M the 1/2 inch, its 3/4 all the way back to the res too. I'm thinking 1/2 because i cracked a fitting on one of the last systems, and had to use the extra 1/2 one that came with the pump.. Careful with those fittings, especially if you use hose clamps.
For the DIY 2" bulkheads, as you know from our DMs, you need:
9 x 2" Carlon brand Male PVC conduit electrical terminal fittings
9 x more female terminal fittings to go with the males
And a pack of size 331 rubber or silicone o-rings.
I'll finish the list off for ya soon, gotta run for now, lol.