magick actually has no colour, it is the intent of the caster that gives it a positive [white] or negative [black] charge. other colours like red magick for love spells or green magick for luck spells are good for remembering what colour corresponds with the spell, or for organizational purposes in a grimoire but again, it's your intent, not the energies colour.
if a spell backfires [positive or negative] it is highly unlikely a loved one would die as a result [especially if you're doing a money spell, think of polar opposites, if you cast a money spell and it backfires, you would lose money. cast a curse and it backfires, you will be cursed. these are extreme examples, but that's what you'll expect something on par with your spell]
granted, you should be specific with money spells. if you say i want thousands of dollars right now' the money has to come from somewhere. it won't start raining from the sky the second you finish casting. you might find the money on the street, get a promotion at work, win the lottery, be offered a new credit card, get a higher interest rate for your savings, find a new job, or get an inheritance after a loved one dies [extreme example, i know, but i can happen] finding 20$ on the street is great for you, but the money came from somewhere. perhaps a millionaire dropped it, or a kid lost their lunch money for the week. you never know. if you feel a money spell is worth it, go for it [i've done many money spells myself] just try to specify what you're hoping for. [say if you work somewhere where you get tips, try saying or visualizing people giving you large tips.]
it's best to think about the spell as a whole and determine if it's all worth it, but don't worry people are going to die, most money spells i've done result in raises or i'm offered a higher interest rate. only once i found money on the street [i did ask at the bank if anyone withdrew the amount but they said no] so i chalked that up to karma rewarding me after a few good deeds on my part that month. most people i know who've done money spells get a couple checks in the mail they were waiting on, a few more jobs, extra tips, or a raise. the key to all of those results however is effort on your part.