Frame:

• Budget Option - TBS Source One v3 (they have a v4, but they made the arms smaller so they don't handle impact as well.). This is an open source frame, which means all the part files are available free online. In other words, you never risk running out of spare parts because worst case if they stop supplying them, you can order them to be cut from a CNC company (and there are a few who specifically cut drone frame parts). This frame is only $27, but it still uses high quality carbon fiber. I would buy two of these frames at once, so you have backup parts of everything.
• High End Option - ImpulseRC Apex - This is a badass and robust freestyle frame, and many consider it to be the best 5" freestyle frame. Now, it does use some unique hardware (that's only available from Australia), so it helps to have spares of essentials on hand. This frame comes with a parts warranty in case you break any carbon on it, you can get the pieces sent to you for the cost of shipping. That said, you could buy almost 4 TBS Source One v3 frames for the cost of one of these, and I think that would do you fine.

Stack: Because of the chip shortage, Flight Controller and ESC stacks are more expensive right now, and stock is in shorter supply. So unfortunately even the 'budget' options are expensive. It really comes down to just finding something that's in stock (although there are a few brands I would avoid). I would argue a solid stack is the most important part of a build, you really don't want it to fail. So the stack I picked there, by T-motor, is a really solid option.

Motors: There are roughly three tiers to motors.

• Budget - Emax Eco 2 - $12-$15 - Made with cheaper parts, but they'll still run smooth. They just don't handle impacts as well, and generally are less powerful because they use weaker magnets. That said, I was pleasantly surprised at how well these perform for the price. I throw these kinds of motors on quads I know I'll be bashing around. I think they're a solid beginner option, because you can buy a few spares for not much more money.
• Mid- Tier - Xnova HardLine - $15-$21 - My go-to price range, a good blend of performance to cost. I put these on any quads I want to fly really well, that may also be crashed (so, my main freestyle quads and some racers). XNova makes high quality motors for a good price compromise.
• High-Tier - T-Motor F40 Pro (2400kv) - $22-$30+ - Made from premium parts and have superior power and response. That said, when a quad hits concrete, even a premium motor has a breaking point. I would only use premium motors on a quad that I had no intention of crashing (something cinematic instead of a freestyle quad I'd hit gaps with). That said, if you have the money, you can feel the performance difference for sure.

Props: Everyone says their props are the best. It's probably similar to debates you'd have over the best tires to drift with. At the end of the day, it's personal preference. You want a 5" prop, but the pitch is subjective. So for starters, I would get a 2 or 3 kinds to try out. I personally like Gemfan brand, but HQ is hugely popular too. My favorite prop is the Gemfan Hurricane 51466 (5.1" diameter, 4.6" pitch). These are a more aggressively pitched prop.

• More pitch = Better response and power at the cost of efficiency (flight time).
• Less pitch = Better efficiency (longer flight times) and smoother control at the cost of power and responsiveness.

Camera: There are different tiers, but honestly the Caddx Ratel 2 is the best I've used for the price.

VTX (Video Transmitter): TBS (TeamBlacksheep) makes the best VTX and radio link tech. So I always get their gear. Of course people will tell you they love whatever they use, but TBS is tried and true. I put two VTXs below. The Pro32 Nano is super small but powerful (400mw broadcasting power). Great if you don't intend to push range at all and want to save weight. If you ever want to fly far though, or through and around objects at distance, there's the Pro32 HV. Bigger, but does over 1W of broadcasting power. I've taken a quad 2 miles out and back without breakup with one of these.

Receiver: This is how your radio talks to your quad. If you are only going to be flying close to yourself (within a few hundred yards), FrSky receivers are fine (R-XSR, XM+, etc). However, they operate on 2.4ghz, which is also the same frequency as many wifi routers. So you can get signal interference, which can knock you out of the sky with no control (which would be terrible at a drift event if you hit a car). There's a better option though, TBS Crossfire. Crossfire operates on a lower radio band (900mhz) to give insane range and signal strength. I think they've done 40mile flights with crossfire to show how badass it is. Basically, you never have to worry about your drone losing its connection to your radio as long as it's set up right. That's why I argue it's the best option if you can't risk your quad falling out of the sky. The only negative is that it's a bit more expensive up front ($70 for the module that sits in your radio, then $30 for the receiver that sits in your drone).

Lipos: You just want something 4S that's 1300-1500mah and over 70C. Those are the only numbers you have to pay attention to. I threw a good option on there.