It's very common for startups to advertise that they provide you with the 'best' hardware, usually Apple, as a perk of the job. 

This could very likely be a warning sign, in my experience.

The idea that someone would sell you a job opportunity, with the notion that they are not going to give you a stone age behemoth, a 640x480 resolution screen, reclaimed high school chairs and a desk made from breeze blocks and planks, and that anything above that is a 'perk' is insanity.

It also likely means that your hire is viewed as a cog that needs to be fitted into the machine, and the necessary equipment you need is seen as a condition that grudgingly must be supplied in order to attract talent. They view the tools that you use as simply a ploy to get you inside, and don't value the difference they make to your working life. 

I am telling you that this is your right. You are expected to work 8-12hr or longer days, remain seated or stationary staring at a device that causes your eyes to dry out and any myriad of other health problems; the 'best' is the absolute minimum required. A fast, efficient machine to work on is not a joyful toy given to pacify - it is a means to professional excellence. It is a means to creative flow. It is a means to doing the best work of your life. 

Now let's talk about the 'best'. Usually its assumed that you will want everything Apple, and maybe this is the case. Maybe you don't want two screens, because one large one works for you. Maybe you just really like Dell machines. But a good employer will understand that Humans taken different things to help them achieve good and sustainable work, so closing that dialog off early could also be a warning sign. 

And on the specifications for the 'best', it should stand to reason that the equipment should be the top of the line possible. If the machine you want can take 16Gb of RAM, then it should be ordered with 16Gb of RAM in it. An 512Gb SSD should be the default.

Some employers will take a wait and see approach to developers complaining that they need more resources, and this is very sad. They are shortchanging themselves, and they are devaluing you and the work that you do. 

Yes this is expensive. But if the company you want to work for values you as a Human, and that you spend a far greater amount of time on the tools you need to do your work than you should, and if they understand that the better the hardware you have to work on can make you more efficient and happier  and more able to do great work, then they are likely to view it as a cost that simply has to be met. 

And that's a company you want to work for.