PowerShell, formatting values in another culture

Is there an easy way in PowerShell to format numbers and the like in another locale? I'm currently writing a few functions to ease SVG generation for me and SVG uses . as a decimal separator, while PowerShell honors my locale settings (de-DE) when converting floating-point numbers to strings.

Is there an easy way to set another locale for a function or so without sticking

.ToString((New-Object Globalization.CultureInfo ""))

after every double variable?

Note: This is about the locale used for formatting, not the format string.

(Side question: Should I use the invariant culture in that case or rather en-US?)

ETA: Well, what I'm trying here is something like the following:

function New-SvgWave([int]$HalfWaves, [double]$Amplitude, [switch]$Upwards) {"<path d='M0,0q0.5,{0} 1,0{1}v1q-0.5,{2} -1,0{3}z'/>" -f (        $(if ($Upwards) {-$Amplitude} else {$Amplitude}),        ("t1,0" * ($HalfWaves - 1)),        $(if ($Upwards -xor ($HalfWaves % 2 -eq 0)) {-$Amplitude} else {$Amplitude}),        ("t-1,0" * ($HalfWaves - 1))    )}

Just a little automation for stuff I tend to write all the time and the double values need to use the decimal point instead of a comma (which they use in my locale).

ETA2: Interesting trivia to add:

PS Home:> $d=1.23PS Home:> $d1,23PS Home:> "$d"1.23

By putting the variable into a string the set locale doesn't seem to apply, somehow.