Hello @gtc,
really? because I looked at their page Weglot Pricing | Translate your website & grow your business and for one language and 10k words is 99$/year, like 8.25$ a month. That could be expensive for your client, but if he needs an ecommerce site in two languages the correct SEO will generate him enough revenue to pay for weglot’s services many times over. Anyway, good luck with whatever you decide. I think there are other options too, check this one out for example [TUTORIAL] Full Multi Language Site - Easy to set-up and to use!