Handmade Lolita is perfectly acceptable, as long as you do a quality job.
The thing about themed or character Lolita is getting the aesthetic right while still keeping with the theme you want. First, you need to consider whether or not the character fits the Lolita aesthetic at all. If they wear bright orange, then there's probably no good way to make it work. But if they already wear black or pastels, then it's not too difficult.
Second, is this supposed to be a Lolita outfit based on the character, or the character wearing Lolita? I personally think that the first can be done successfully, but it takes a lot of planning and work. Choosing things like colors and accessories is what will make it look good--for example, there's a great Sailor Moon themed Lolita coordinate that floats around Tumblr a lot that I think is perfect. She wears a navy sailor dress (I think it's Meta) with a red bow and transformation brooch. The dress is still authentically Lolita, but the accessories and color scheme is what makes it for the character.
The character wearing Lolita is a little different, and I personally think only appropriate for conventions. Think about what style the character would wear, and then make a dress that is correct for that style. Then you would basically just wear the dress with the character wig/makeup.
As long as you do your research well and make sure that the silhouette and quality are in keeping with the style, you should be fine.
Kiryuin Satsuki [Kill la Kill] 40% - AX 2014
Super Sailor Uranus [Sailor Moon SuperS] 60% - Anime Conji 2014
Nuriko [Fushigi Yuugi] 15% - AX 2014
The Fashionable Cupcake