So hello there! I'm planning to buy a new flute since mine, some cheapo one from China, started to fail playing any note lower than G, and the repairman I asked said it could be repaired, but he also said I'm better off buying a new one instead of wasting my money on repairing a hopeless one.

So now I looked at online sellers (I can't really buy stuff from physical stores because they don't sell any of what you can call the reputable brands) here in the Philippines, and I've become interested in three.

1. Yamaha F100 SII (6000PHP = around 140USD)
The seller didn't say much about it, just that it's a vintage one. I already contacted the seller to get more info about it.

2. Selmer Bundy (3850PHP = around 90USD)
The seller said that the original pads are in good condition ("played and tested") and can play from the lowest to highest note, and looks good as new save for some minor scratches.

3. Gemeinhardt (6500PHP = around 150USD)
The seller claimed that the flute is in very good condition, and that it doesn't have major scratches and stuff. It has Gemeinhardt ELKHARD, IND. M2 B38022 [or maybe it was B38072, the picture wasn't that clear] in the tenon.

I'm self-studying and I have no idea which of these is the better buy. My budget is quite low since I'm reserving some of my money for repair work--just in case that whatever I'll buy has some problems. Hope you can help me. Thanks!

None of those are at all good. They're all extremely cheap, and second-hand from anonymous sellers on the internet. Not the most reliable source for a good instrument. If you think you can find a reliable instrument for under 200 US dollars, you are sadly misinformed. I would recommend looking for a new instrument in the 600-1500 US dollar range. Any brand new Yamaha in the 200-400 series would be great, as well as an Amadeus by Haynes 600 or 700, any Pearl Quantz, or an Azumi 1000 model. Since you're self taught, I would personally recommend a Yamaha 300 or an Amadeus 600. They would be between 1000 and 1500 US dollars, both open-holed but come with plugs, available with a b foot, and both have silver head joints and nickel bodies. Gemeinhardt is a very poor quality brand, and whether you buy new or not, it would cost more in repairs after a year or two than the flute itself cost.

Just to add, it really is not in your best interest as a flutist to reserve money to repair a flute you just bought. You should avoid putting yourself in a situation where all of your choices could potentially need repairs and/or be unplayable when you get it.