I've attended 3 or 4 funerals in Germany in the past years and one thing I noticed was that at least the male relatives all wore suits. Many of them looked like they would never normally wear a suit in their life, some had extremely cheap-looking suits probably bought for the occasion and many of the suits were probably hanging in the wardrobe for 20 years or so, yet they made the effort. And then there were the people who just wore anything. I can't help it, but somehow I had the impression they were too cheap to dress up.
Especially when going to a foreign country, I'd try to make the best impression possible. I wouldn't feel comfortable if my relatives would be saying - "look, he came all the way from X, but he was too cheap to buy himself proper attire." - and believe me, people do talk about such things on such events, sometimes even for years.
OP, don't you have the kind of shops in Canada that sell some suits for $ 99 or so which you might donate to charity afterwards? If not, you might buy one it Germany for € 59. Link