Since I don't even know when people started doing custom tokens. The first ones being sold were made by some fans I guess who just figured out that a picture printed on a piece of paper and foiled is a good idea (we also have altered cards like this via print). These type of custom tokens are available kind of everywhere one looks. But majority of those tokens are really horrible (things changed in past few years, so maybe I should use the past tense). Anyway just check ebay or MKM or well just google Magic custom tokens. Many people do custom tokens in a way that they steal art and print it and create some layout for the token. Those are the worst most of the time and many times the tokens are foil (half naked female character tokens that are shiny...simply sell...no matter of the quality). Horrible to look at from my point of view and I can't even imagine paying 5USD for such a token. Ok, yes I admit it usually features a hardly clad female character no matter if the token is Insect, Beast, Elemental or Soldier - the less armor the better^_^) so I may not be in the market's target group.
Example of token I do not like, do you?
Do you see a Green Elf?
Lately not only big portals like SCG or ChannelFireball have their own tokens. Freelance artists or shops (hiring someone to do the tokens) start selling their own tokens and they are making quite a big business out of that (I just wonder why bother selling singles sometimes...). I'm seriously wondering about this 'business' myself but since I cannot draw or paint well I'm not really sure if anyone would be interested (at least in this country my work is most of the time looked down upon). It still might happen.
But even among all those people producing their own tokens I had difficulties finding ones that I would actually like. I am always in wonder why people buy many of those tokens I find really ugly (and oftentimes foil). Anime styled tokens are also popular (usually portraying almost naked female characters no matter if it is a wolf or beast, but in this case it is more understandable). But even if those tokens are painted/drawn by someone the quality is low (probably because the person does not get paid much, or rather someone of not such a good skill does those). Some are ok even though I don't like them but if I would want to use something as tokens I would like to find something nice to look at, something that will be right away distinguished as the corresponding creature etc. Many times one cannot even distinguish what kind of token the card represents. I would not consider myself picky about this but after all I've seen I might actually be. But what I only want from a token is this -> the image should correspond the creature it represents (if the color palette corresponds the color that's a bonus), the design should be clean, the overall look should not be too distracting (that means no really shiny foils, too flashy images on which one cannot even distinguish what is painted on it etc). If there are no tokens like this I'd rather play with a piece of paper on which I type the power and toughness (and possibly the name/type of the token and its abilites).
But among all those horrible tokens, official ones both regular and promo we can also find tokens that are actually pretty cool. The very first tokens I actually liked were from Inkwell Looter unfortunately for us he discontinued his Magic related project and moved on to something better. For a long time I couldn't find any other token I would like (I actually like SCG tokens quite a lot) till Rishada (one of Czech shops started selling and distributing Yummy tokens). I got the first token at Grand Prix Utrecht were I received a promo version of one token. At another GP I got another one. Later I've seen the whole (non-promo) batch and immediately fell in love with those.
This kind of style is something I would not expect to like. I write this because Inkwell Looter's style is similar and some of you could expect that I like this particular style. My preferred style would be anything similar to Drew Baker's style, check out his work! But well just look at those Yummy tokens. All those pics are funny and distinctive. She did a great job. The graphics design is one of the best if not the best as well. The paper could be different as this one is too sturdy for my like but I guess that is problem of all tokens out there.
So those are my two cents about custom tokens. Each of us has a different taste but when buying custom tokens I'd rather support someone who actually paints or draws the tokens himself/herself. So if you like these tokens you can visit their site at http://yummytokens.eu/index.php and possibly buy some of those pretty neat tokens.